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msmarco_v2.1_doc_00_10705671#14_15571221
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http://2012books.lardbucket.org/books/beginning-chemistry/s14-02-phase-transitions-melting-boil.html
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Phase Transitions: Melting, Boiling, and Subliming
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10.2
Phase Transitions: Melting, Boiling, and Subliming
10.2 Phase Transitions: Melting, Boiling, and Subliming
Learning Objectives
Example 2
Example 3
Key Takeaways
Exercises
Answers
|
To determine the magnitude of the energy change, we must first convert the amount of Br 2 to moles. Then we can use Δ Hvap as a conversion factor. 66.7 g Br 2 × 1 mol Br 2 159.8 g × 15.4 kJ mol = 6.43 kJ
Because the process is exothermic, the actual value will be negative: Δ H = −6.43 kJ.
Test Yourself
What is the energy change when 822 g of C 2 H 5 OH (ℓ) boil at its normal boiling point of 78.3°C? Answer
689 kJ
As with melting, the energy in boiling goes exclusively to changing the phase of a substance; it does not go into changing the temperature of a substance. So boiling is also an isothermal process. Only when all of a substance has boiled does any additional energy go to changing its temperature. What happens when a liquid becomes a gas? We have already established that a liquid is composed of particles in contact with each other.
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Phase Transitions: Melting, Boiling, and Subliming
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10.2
Phase Transitions: Melting, Boiling, and Subliming
10.2 Phase Transitions: Melting, Boiling, and Subliming
Learning Objectives
Example 2
Example 3
Key Takeaways
Exercises
Answers
|
it does not go into changing the temperature of a substance. So boiling is also an isothermal process. Only when all of a substance has boiled does any additional energy go to changing its temperature. What happens when a liquid becomes a gas? We have already established that a liquid is composed of particles in contact with each other. When a liquid becomes a gas, the particles separate from each other, with each particle going its own way in space. This is how gases tend to fill their containers. Indeed, in the gas phase most of the volume is empty space; only about 1/1,000th of the volume is actually taken up by matter ( Figure 10.4 "Liquids and Gases" ). It is this property of gases that explains why they can be compressed, a fact that is considered in Chapter 6 "Gases".
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http://2012books.lardbucket.org/books/beginning-chemistry/s14-02-phase-transitions-melting-boil.html
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Phase Transitions: Melting, Boiling, and Subliming
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10.2
Phase Transitions: Melting, Boiling, and Subliming
10.2 Phase Transitions: Melting, Boiling, and Subliming
Learning Objectives
Example 2
Example 3
Key Takeaways
Exercises
Answers
|
When a liquid becomes a gas, the particles separate from each other, with each particle going its own way in space. This is how gases tend to fill their containers. Indeed, in the gas phase most of the volume is empty space; only about 1/1,000th of the volume is actually taken up by matter ( Figure 10.4 "Liquids and Gases" ). It is this property of gases that explains why they can be compressed, a fact that is considered in Chapter 6 "Gases". Figure 10.4 Liquids and Gases
In (a), the particles are a liquid; the particles are in contact but are also able to move around each other. In (b), the particles are a gas, and most of the volume is actually empty space. The particles are not to scale; in reality, the dots representing the particles would be about 1/100th the size as depicted.
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http://2012books.lardbucket.org/books/beginning-chemistry/s14-02-phase-transitions-melting-boil.html
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Phase Transitions: Melting, Boiling, and Subliming
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10.2
Phase Transitions: Melting, Boiling, and Subliming
10.2 Phase Transitions: Melting, Boiling, and Subliming
Learning Objectives
Example 2
Example 3
Key Takeaways
Exercises
Answers
|
Figure 10.4 Liquids and Gases
In (a), the particles are a liquid; the particles are in contact but are also able to move around each other. In (b), the particles are a gas, and most of the volume is actually empty space. The particles are not to scale; in reality, the dots representing the particles would be about 1/100th the size as depicted. Under some circumstances, the solid phase can transition directly to the gas phase without going through a liquid phase, and a gas can directly become a solid. The solid-to-gas change is called sublimation
The process of a solid becoming a gas. , while the reverse process is called deposition
The process of a gas becoming a solid. . Sublimation is isothermal, like the other phase changes.
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http://2012books.lardbucket.org/books/beginning-chemistry/s14-02-phase-transitions-melting-boil.html
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Phase Transitions: Melting, Boiling, and Subliming
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10.2
Phase Transitions: Melting, Boiling, and Subliming
10.2 Phase Transitions: Melting, Boiling, and Subliming
Learning Objectives
Example 2
Example 3
Key Takeaways
Exercises
Answers
|
Under some circumstances, the solid phase can transition directly to the gas phase without going through a liquid phase, and a gas can directly become a solid. The solid-to-gas change is called sublimation
The process of a solid becoming a gas. , while the reverse process is called deposition
The process of a gas becoming a solid. . Sublimation is isothermal, like the other phase changes. There is a measurable energy change during sublimation; this energy change is called the enthalpy of sublimation
The amount of energy needed to change from a solid to a gas or from a gas to a solid. , represented as Δ Hsub. The relationship between the Δ Hsub and the other enthalpy changes is as follows: ΔHsub = ΔHfus + ΔHvap
As such, Δ Hsub is not always tabulated because it can be simply calculated from Δ Hfus and Δ Hvap.
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Phase Transitions: Melting, Boiling, and Subliming
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10.2
Phase Transitions: Melting, Boiling, and Subliming
10.2 Phase Transitions: Melting, Boiling, and Subliming
Learning Objectives
Example 2
Example 3
Key Takeaways
Exercises
Answers
|
There is a measurable energy change during sublimation; this energy change is called the enthalpy of sublimation
The amount of energy needed to change from a solid to a gas or from a gas to a solid. , represented as Δ Hsub. The relationship between the Δ Hsub and the other enthalpy changes is as follows: ΔHsub = ΔHfus + ΔHvap
As such, Δ Hsub is not always tabulated because it can be simply calculated from Δ Hfus and Δ Hvap. There are several common examples of sublimation. A well-known product—dry ice—is actually solid CO 2. Dry ice is dry because it sublimes, with the solid bypassing the liquid phase and going straight to the gas phase. The sublimation occurs at temperature of −77°C, so it must be handled with caution. If you have ever noticed that ice cubes in a freezer tend to get smaller over time, it is because the solid water is very slowly subliming. “
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Phase Transitions: Melting, Boiling, and Subliming
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10.2
Phase Transitions: Melting, Boiling, and Subliming
10.2 Phase Transitions: Melting, Boiling, and Subliming
Learning Objectives
Example 2
Example 3
Key Takeaways
Exercises
Answers
|
There are several common examples of sublimation. A well-known product—dry ice—is actually solid CO 2. Dry ice is dry because it sublimes, with the solid bypassing the liquid phase and going straight to the gas phase. The sublimation occurs at temperature of −77°C, so it must be handled with caution. If you have ever noticed that ice cubes in a freezer tend to get smaller over time, it is because the solid water is very slowly subliming. “ Freezer burn” isn’t actually a burn; it occurs when certain foods, such as meats, slowly lose solid water content because of sublimation. The food is still goo
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http://2012books.lardbucket.org/books/beginning-chemistry/s16-01-arrhenius-acids-and-bases.html
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Identify an Arrhenius acid and an Arrhenius base. Write the chemical reaction between an Arrhenius acid and an Arrhenius base. Historically, the first chemical definition of an acid and a base was put forward by Svante Arrhenius, a Swedish chemist, in 1884. An Arrhenius acid
A compound that increases the hydrogen ion concentration in aqueous solution. is a compound that increases the H + ion concentration in aqueous solution. The H + ion is just a bare proton, and it is rather clear that bare protons are not floating around in an aqueous solution. Instead, chemistry has defined the hydronium ion
The actual chemical species that represents a hydrogen ion. (H 3 O +) as the actual chemical species that represents an H + ion. H + ions and H 3 O + ions are often considered interchangeable when writing chemical equations (although a properly balanced chemical equation should also include the additional H 2 O). Classic Arrhenius acids can be considered ionic compounds in which H + is the cation.
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
The H + ion is just a bare proton, and it is rather clear that bare protons are not floating around in an aqueous solution. Instead, chemistry has defined the hydronium ion
The actual chemical species that represents a hydrogen ion. (H 3 O +) as the actual chemical species that represents an H + ion. H + ions and H 3 O + ions are often considered interchangeable when writing chemical equations (although a properly balanced chemical equation should also include the additional H 2 O). Classic Arrhenius acids can be considered ionic compounds in which H + is the cation. Table 12.1 "Some Arrhenius Acids" lists some Arrhenius acids and their names. Table 12.1 Some Arrhenius Acids
Formula
Name
HC 2 H 3 O 2 (also written CH 3 COOH)
acetic acid
HClO 3
chloric acid
HCl
hydrochloric acid
HBr
hydrobromic acid
HI
hydriodic acid
HF
hydrofluoric acid
HNO 3
nitric acid
H 2 C 2 O 4
oxalic acid
HClO 4
perchloric acid
H 3 PO 4
phosphoric acid
H 2 SO 4
sulfuric acid
H 2 SO 3
sulfurous acid
An Arrhenius base
A compound that increases the hydroxide ion concentration in aqueous solution. is a compound that increases the OH − ion concentration in aqueous solution. Ionic compounds of the OH − ion are classic Arrhenius bases. Example 1
Identify each compound as an Arrhenius acid, an Arrhenius base, or neither.
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
Table 12.1 "Some Arrhenius Acids" lists some Arrhenius acids and their names. Table 12.1 Some Arrhenius Acids
Formula
Name
HC 2 H 3 O 2 (also written CH 3 COOH)
acetic acid
HClO 3
chloric acid
HCl
hydrochloric acid
HBr
hydrobromic acid
HI
hydriodic acid
HF
hydrofluoric acid
HNO 3
nitric acid
H 2 C 2 O 4
oxalic acid
HClO 4
perchloric acid
H 3 PO 4
phosphoric acid
H 2 SO 4
sulfuric acid
H 2 SO 3
sulfurous acid
An Arrhenius base
A compound that increases the hydroxide ion concentration in aqueous solution. is a compound that increases the OH − ion concentration in aqueous solution. Ionic compounds of the OH − ion are classic Arrhenius bases. Example 1
Identify each compound as an Arrhenius acid, an Arrhenius base, or neither. HNO 3
CH 3 OH
Mg (OH) 2
Solution
This compound is an ionic compound between H + ions and NO 3− ions, so it is an Arrhenius acid. Although this formula has an OH in it, we do not recognize the remaining part of the molecule as a cation. It is neither an acid nor a base. ( In fact, it is the formula for methanol, an organic compound.) This formula also has an OH in it, but this time we recognize that the magnesium is present as Mg 2+ cations.
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
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HNO 3
CH 3 OH
Mg (OH) 2
Solution
This compound is an ionic compound between H + ions and NO 3− ions, so it is an Arrhenius acid. Although this formula has an OH in it, we do not recognize the remaining part of the molecule as a cation. It is neither an acid nor a base. ( In fact, it is the formula for methanol, an organic compound.) This formula also has an OH in it, but this time we recognize that the magnesium is present as Mg 2+ cations. As such, this is an ionic compound of the OH − ion and is an Arrhenius base. Test Yourself
Identify each compound as an Arrhenius acid, an Arrhenius base, or neither. KOH
H 2 SO 4
C 2 H 6
Answer
Arrhenius base
Arrhenius acid
neither
Acids have some properties in common. They turn litmus, a plant extract, red. They react with some metals to give off H 2 gas.
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
As such, this is an ionic compound of the OH − ion and is an Arrhenius base. Test Yourself
Identify each compound as an Arrhenius acid, an Arrhenius base, or neither. KOH
H 2 SO 4
C 2 H 6
Answer
Arrhenius base
Arrhenius acid
neither
Acids have some properties in common. They turn litmus, a plant extract, red. They react with some metals to give off H 2 gas. They react with carbonate and hydrogen carbonate salts to give off CO 2 gas. Acids that are ingested typically have a sour, sharp taste. ( The name acid comes from the Latin word acidus, meaning “sour.”) Bases also have some properties in common. They are slippery to the touch, turn litmus blue, and have a bitter flavor if ingested.
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
They react with carbonate and hydrogen carbonate salts to give off CO 2 gas. Acids that are ingested typically have a sour, sharp taste. ( The name acid comes from the Latin word acidus, meaning “sour.”) Bases also have some properties in common. They are slippery to the touch, turn litmus blue, and have a bitter flavor if ingested. Acids and bases have another property: they react with each other to make water and an ionic compound called a salt. A salt
Any ionic compound that is formed from a reaction between an acid and a base. , in chemistry, is any ionic compound made by combining an acid with a base. A reaction between an acid and a base is called a neutralization reaction
The reaction of an acid and a base to produce water and a salt.
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
Acids and bases have another property: they react with each other to make water and an ionic compound called a salt. A salt
Any ionic compound that is formed from a reaction between an acid and a base. , in chemistry, is any ionic compound made by combining an acid with a base. A reaction between an acid and a base is called a neutralization reaction
The reaction of an acid and a base to produce water and a salt. and can be represented as follows: acid + base → H2O + salt
The stoichiometry of the balanced chemical equation depends on the number of H + ions in the acid and the number of OH − ions in the base. Example 2
Write the balanced chemical equation for the neutralization reaction between H 2 SO 4 and KOH. What is the name of the salt that is formed? Solution
The general reaction is as follows:
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
and can be represented as follows: acid + base → H2O + salt
The stoichiometry of the balanced chemical equation depends on the number of H + ions in the acid and the number of OH − ions in the base. Example 2
Write the balanced chemical equation for the neutralization reaction between H 2 SO 4 and KOH. What is the name of the salt that is formed? Solution
The general reaction is as follows: H2SO4 + KOH → H2O + salt
Because the acid has two H + ions in its formula, we need two OH − ions to react with it, making two H 2 O molecules as product. The remaining ions, K + and SO 42−, make the salt potassium sulfate (K 2 SO 4 ). The balanced chemical reaction is as follows: H2SO4 + 2KOH → 2H2O + K2SO4
Test Yourself
Write the balanced chemical equation for the neutralization reaction between HCl and Mg (OH) 2. What is the name of the salt that is formed?
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
H2SO4 + KOH → H2O + salt
Because the acid has two H + ions in its formula, we need two OH − ions to react with it, making two H 2 O molecules as product. The remaining ions, K + and SO 42−, make the salt potassium sulfate (K 2 SO 4 ). The balanced chemical reaction is as follows: H2SO4 + 2KOH → 2H2O + K2SO4
Test Yourself
Write the balanced chemical equation for the neutralization reaction between HCl and Mg (OH) 2. What is the name of the salt that is formed? Answer
2HCl + Mg (OH) 2 → 2H 2 O + MgCl 2; magnesium chloride
Key Takeaways
An Arrhenius acid is a compound that increases the H + ion concentration in aqueous solution. An Arrhenius base is a compound that increases the OH − ion concentration in aqueous solution. The reaction between an Arrhenius acid and an Arrhenius base is called neutralization and results in the formation of water and a salt. Exercises
Define Arrhenius acid.
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
Answer
2HCl + Mg (OH) 2 → 2H 2 O + MgCl 2; magnesium chloride
Key Takeaways
An Arrhenius acid is a compound that increases the H + ion concentration in aqueous solution. An Arrhenius base is a compound that increases the OH − ion concentration in aqueous solution. The reaction between an Arrhenius acid and an Arrhenius base is called neutralization and results in the formation of water and a salt. Exercises
Define Arrhenius acid. Define Arrhenius base. What are some general properties of Arrhenius acids? What are some general properties of Arrhenius bases? Identify each substance as an Arrhenius acid, an Arrhenius base, or neither. NaOH
C 2 H 5 OH
H 3 PO 4
Identify each substance as an Arrhenius acid, an Arrhenius base, or neither.
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
Define Arrhenius base. What are some general properties of Arrhenius acids? What are some general properties of Arrhenius bases? Identify each substance as an Arrhenius acid, an Arrhenius base, or neither. NaOH
C 2 H 5 OH
H 3 PO 4
Identify each substance as an Arrhenius acid, an Arrhenius base, or neither. C 6 H 12 O 6
HNO 2
Ba (OH) 2
Write the balanced chemical equation for the neutralization reaction between KOH and H 2 C 2 O 4. What is the salt? Write the balanced chemical equation for the neutralization reaction between Sr (OH) 2 and H 3 PO 4. What is the salt? Write the balanced chemical equation for the neutralization reaction between HCl and Fe (OH) 3.
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
C 6 H 12 O 6
HNO 2
Ba (OH) 2
Write the balanced chemical equation for the neutralization reaction between KOH and H 2 C 2 O 4. What is the salt? Write the balanced chemical equation for the neutralization reaction between Sr (OH) 2 and H 3 PO 4. What is the salt? Write the balanced chemical equation for the neutralization reaction between HCl and Fe (OH) 3. What is the salt? Write the balanced chemical equation for the neutralization reaction between H 2 SO 4 and Cr (OH) 3. What is the salt? CaCl 2 would be the product of the reaction of what acid and what base? Zn (NO 3) 2 would be product of the reaction of what acid and what base?
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Arrhenius Acids and Bases
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12.1
Arrhenius Acids and Bases
12.1 Arrhenius Acids and Bases
Learning Objectives
Example 1
Example 2
Key Takeaways
Exercises
Answers
|
What is the salt? Write the balanced chemical equation for the neutralization reaction between H 2 SO 4 and Cr (OH) 3. What is the salt? CaCl 2 would be the product of the reaction of what acid and what base? Zn (NO 3) 2 would be product of the reaction of what acid and what base? BaSO 4 would be product of the reaction of what acid and what base? Na 3 PO 4 would be product of the reaction of what acid and what base? Answers
a compound that increases the H + concentration in water
sour taste, react with metals, and turn litmus red
Arrhenius base
neither
Arrhenius acid
2KOH + H 2 C 2 O 4 → 2H 2 O + K 2 C 2 O 4; K 2 C 2 O 4
3HCl + Fe (OH) 3 → 3H 2 O + FeCl 3; FeCl 3
HCl and Ca (OH) 2
H 2 SO 4 and Ba (OH) 2
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Strong and Weak Acids and Bases and Their Salts
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
|
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Define a strong and a weak acid and base. Recognize an acid or a base as strong or weak. Determine if a salt produces an acidic or a basic solution. Except for their names and formulas, so far we have treated all acids as equals, especially in a chemical reaction. However, acids can be very different in a very important way. Consider HCl (aq). When HCl is dissolved in H 2 O, it completely dissociates into H + (aq) and Cl − (aq) ions; all the HCl molecules become ions: HCl → 100% H + (aq) + Cl − (aq)
Any acid that dissociates 100% into ions is called a strong acid
Any acid that is 100% dissociated into ions in aqueous solution. .
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Strong and Weak Acids and Bases and Their Salts
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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Consider HCl (aq). When HCl is dissolved in H 2 O, it completely dissociates into H + (aq) and Cl − (aq) ions; all the HCl molecules become ions: HCl → 100% H + (aq) + Cl − (aq)
Any acid that dissociates 100% into ions is called a strong acid
Any acid that is 100% dissociated into ions in aqueous solution. . If it does not dissociate 100%, it is a weak acid
Any acid that is less than 100% dissociated into ions in aqueous solution. . HC 2 H 3 O 2 is an example of a weak acid: HC 2 H 3 O 2 → ~ 5 % H + (aq) + C 2 H 3 O 2 − (aq)
Because this reaction does not go 100% to completion, it is more appropriate to write it as an equilibrium: HC 2 H 3 O 2 ⇄ H + (aq) + C 2 H 3 O 2 − (aq)
As it turns out, there are very few strong acids, which are given in Table 12.2 "Strong Acids and Bases".
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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If it does not dissociate 100%, it is a weak acid
Any acid that is less than 100% dissociated into ions in aqueous solution. . HC 2 H 3 O 2 is an example of a weak acid: HC 2 H 3 O 2 → ~ 5 % H + (aq) + C 2 H 3 O 2 − (aq)
Because this reaction does not go 100% to completion, it is more appropriate to write it as an equilibrium: HC 2 H 3 O 2 ⇄ H + (aq) + C 2 H 3 O 2 − (aq)
As it turns out, there are very few strong acids, which are given in Table 12.2 "Strong Acids and Bases". If an acid is not listed here, it is a weak acid. It may be 1% ionized or 99% ionized, but it is still classified as a weak acid. The issue is similar with bases: a strong base
Any base that is 100% dissociated into ions in aqueous solution. is a base that is 100% ionized in solution.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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If an acid is not listed here, it is a weak acid. It may be 1% ionized or 99% ionized, but it is still classified as a weak acid. The issue is similar with bases: a strong base
Any base that is 100% dissociated into ions in aqueous solution. is a base that is 100% ionized in solution. If it is less than 100% ionized in solution, it is a weak base
Any base that is less than 100% dissociated into ions in aqueous solution. . There are very few strong bases (see Table 12.2 "Strong Acids and Bases" ); any base not listed is a weak base. All strong bases are OH – compounds.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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If it is less than 100% ionized in solution, it is a weak base
Any base that is less than 100% dissociated into ions in aqueous solution. . There are very few strong bases (see Table 12.2 "Strong Acids and Bases" ); any base not listed is a weak base. All strong bases are OH – compounds. So a base based on some other mechanism, such as NH 3 (which does not contain OH − ions as part of its formula), will be a weak base. Table 12.2 Strong Acids and Bases
Acids
Bases
HCl
LiOH
HBr
NaOH
HI
KOH
HNO 3
RbOH
H 2 SO 4
CsOH
HClO 3
Mg (OH) 2
HClO 4
Ca (OH) 2
Sr (OH) 2
Ba (OH) 2
Example 6
Identify each acid or base as strong or weak. HCl
Mg (OH) 2
C 5 H 5 N
Solution
Because HCl is listed in Table 12.2 "Strong Acids and Bases", it is a strong acid. Because Mg (OH) 2 is listed in Table 12.2 "Strong Acids and Bases", it is a strong base. The nitrogen in C 5 H 5 N would act as a proton acceptor and therefore can be considered a base, but because it does not contain an OH compound, it cannot be considered a strong base;
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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So a base based on some other mechanism, such as NH 3 (which does not contain OH − ions as part of its formula), will be a weak base. Table 12.2 Strong Acids and Bases
Acids
Bases
HCl
LiOH
HBr
NaOH
HI
KOH
HNO 3
RbOH
H 2 SO 4
CsOH
HClO 3
Mg (OH) 2
HClO 4
Ca (OH) 2
Sr (OH) 2
Ba (OH) 2
Example 6
Identify each acid or base as strong or weak. HCl
Mg (OH) 2
C 5 H 5 N
Solution
Because HCl is listed in Table 12.2 "Strong Acids and Bases", it is a strong acid. Because Mg (OH) 2 is listed in Table 12.2 "Strong Acids and Bases", it is a strong base. The nitrogen in C 5 H 5 N would act as a proton acceptor and therefore can be considered a base, but because it does not contain an OH compound, it cannot be considered a strong base; it is a weak base. Test Yourself
Identify each acid or base as strong or weak. RbOH
HNO 2
Answers
strong base
weak acid
Example 7
Write the balanced chemical equation for the dissociation of Ca (OH) 2 and indicate whether it proceeds 100% to products or not. Solution
This is an ionic compound of Ca 2+ ions and OH − ions. When an ionic compound dissolves, it separates into its constituent ions:
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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it is a weak base. Test Yourself
Identify each acid or base as strong or weak. RbOH
HNO 2
Answers
strong base
weak acid
Example 7
Write the balanced chemical equation for the dissociation of Ca (OH) 2 and indicate whether it proceeds 100% to products or not. Solution
This is an ionic compound of Ca 2+ ions and OH − ions. When an ionic compound dissolves, it separates into its constituent ions: Ca (OH)2 → Ca2+(aq) + 2OH−(aq)
Because Ca (OH) 2 is listed in Table 12.2 "Strong Acids and Bases", this reaction proceeds 100% to products. Test Yourself
Write the balanced chemical equation for the dissociation of hydrazoic acid (HN 3) and indicate whether it proceeds 100% to products or not. Answer
The reaction is as follows: HN3 → H+(aq) + N3−(aq)
It does not proceed 100% to products because hydrazoic acid is not a strong acid. Certain salts will also affect the acidity or basicity of aqueous solutions because some of the ions will undergo hydrolysis, just like NH 3 does to make a basic solution.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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Ca (OH)2 → Ca2+(aq) + 2OH−(aq)
Because Ca (OH) 2 is listed in Table 12.2 "Strong Acids and Bases", this reaction proceeds 100% to products. Test Yourself
Write the balanced chemical equation for the dissociation of hydrazoic acid (HN 3) and indicate whether it proceeds 100% to products or not. Answer
The reaction is as follows: HN3 → H+(aq) + N3−(aq)
It does not proceed 100% to products because hydrazoic acid is not a strong acid. Certain salts will also affect the acidity or basicity of aqueous solutions because some of the ions will undergo hydrolysis, just like NH 3 does to make a basic solution. The general rule is that salts with ions that are part of strong acids or bases will not hydrolyze, while salts with ions that are part of weak acids or bases will hydrolyze. Consider NaCl. When it dissolves in an aqueous solution, it separates into Na + ions and Cl − ions: NaCl → Na+(aq) + Cl−(aq)
Will the Na + (aq) ion hydrolyze? If it does, it will interact with the OH − ion to make NaOH:
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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The general rule is that salts with ions that are part of strong acids or bases will not hydrolyze, while salts with ions that are part of weak acids or bases will hydrolyze. Consider NaCl. When it dissolves in an aqueous solution, it separates into Na + ions and Cl − ions: NaCl → Na+(aq) + Cl−(aq)
Will the Na + (aq) ion hydrolyze? If it does, it will interact with the OH − ion to make NaOH: Na+(aq) + H2O → NaOH + H+(aq)
However, NaOH is a strong base, which means that it is 100% ionized in solution: NaOH → Na+(aq) + OH−(aq)
The free OH − (aq) ion reacts with the H + (aq) ion to remake a water molecule: H+(aq) + OH−(aq) → H2O
The net result? There is no change, so there is no effect on the acidity or basicity of the solution from the Na + (aq) ion. What about the Cl − ion?
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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Na+(aq) + H2O → NaOH + H+(aq)
However, NaOH is a strong base, which means that it is 100% ionized in solution: NaOH → Na+(aq) + OH−(aq)
The free OH − (aq) ion reacts with the H + (aq) ion to remake a water molecule: H+(aq) + OH−(aq) → H2O
The net result? There is no change, so there is no effect on the acidity or basicity of the solution from the Na + (aq) ion. What about the Cl − ion? Will it hydrolyze? If it does, it will take an H + ion from a water molecule: Cl−(aq) + H2O → HCl + OH−
However, HCl is a strong acid, which means that it is 100% ionized in solution: HCl → H+(aq) + Cl−(aq)
The free H + (aq) ion reacts with the OH − (aq) ion to remake a water molecule: H+(aq) + OH−(aq) → H2O
The net result?
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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Will it hydrolyze? If it does, it will take an H + ion from a water molecule: Cl−(aq) + H2O → HCl + OH−
However, HCl is a strong acid, which means that it is 100% ionized in solution: HCl → H+(aq) + Cl−(aq)
The free H + (aq) ion reacts with the OH − (aq) ion to remake a water molecule: H+(aq) + OH−(aq) → H2O
The net result? There is no change, so there is no effect on the acidity or basicity of the solution from the Cl − (aq) ion. Because neither ion in NaCl affects the acidity or basicity of the solution, NaCl is an example of a neutral salt
An ionic compound that does not affect the acidity of its aqueous solution. . Things change, however, when we consider a salt like NaC 2 H 3 O 2. We already know that the Na + ion won’t affect the acidity of the solution.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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There is no change, so there is no effect on the acidity or basicity of the solution from the Cl − (aq) ion. Because neither ion in NaCl affects the acidity or basicity of the solution, NaCl is an example of a neutral salt
An ionic compound that does not affect the acidity of its aqueous solution. . Things change, however, when we consider a salt like NaC 2 H 3 O 2. We already know that the Na + ion won’t affect the acidity of the solution. What about the acetate ion? If it hydrolyzes, it will take an H + from a water molecule: C2H3O2−(aq) + H2O → HC2H3O2 + OH−(aq)
Does this happen? Yes, it does. Why?
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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What about the acetate ion? If it hydrolyzes, it will take an H + from a water molecule: C2H3O2−(aq) + H2O → HC2H3O2 + OH−(aq)
Does this happen? Yes, it does. Why? Because HC2H3O2 is a weak acid. Any chance a weak acid has to form, it will (the same with a weak base). As some C 2 H 3 O 2− ions hydrolyze with H 2 O to make the molecular weak acid, OH − ions are produced. OH − ions make solutions basic. Thus NaC 2 H 3 O 2 solutions are slightly basic, so such a salt is called a basic salt
An ionic compound whose aqueous solution is slightly basic.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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Because HC2H3O2 is a weak acid. Any chance a weak acid has to form, it will (the same with a weak base). As some C 2 H 3 O 2− ions hydrolyze with H 2 O to make the molecular weak acid, OH − ions are produced. OH − ions make solutions basic. Thus NaC 2 H 3 O 2 solutions are slightly basic, so such a salt is called a basic salt
An ionic compound whose aqueous solution is slightly basic. . There are also salts whose aqueous solutions are slightly acidic. NH 4 Cl is an example. When NH 4 Cl is dissolved in H 2 O, it separates into NH 4+ ions and Cl − ions. We have already seen that the Cl − ion does not hydrolyze.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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. There are also salts whose aqueous solutions are slightly acidic. NH 4 Cl is an example. When NH 4 Cl is dissolved in H 2 O, it separates into NH 4+ ions and Cl − ions. We have already seen that the Cl − ion does not hydrolyze. However, the NH 4+ ion will: NH4+(aq) + H2O → NH3(aq) + H3O+(aq)
Recall from Section 12.1 "Arrhenius Acids and Bases" that H 3 O + ion is the hydronium ion, the more chemically proper way to represent the H + ion. This is the classic acid species in solution, so a solution of NH 4+ (aq) ions is slightly acidic. NH 4 Cl is an example of an acid salt
An ionic compound whose aqueous solution is slightly acidic. .
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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However, the NH 4+ ion will: NH4+(aq) + H2O → NH3(aq) + H3O+(aq)
Recall from Section 12.1 "Arrhenius Acids and Bases" that H 3 O + ion is the hydronium ion, the more chemically proper way to represent the H + ion. This is the classic acid species in solution, so a solution of NH 4+ (aq) ions is slightly acidic. NH 4 Cl is an example of an acid salt
An ionic compound whose aqueous solution is slightly acidic. . The molecule NH 3 is a weak base, and it will form when it can, just like a weak acid will form when it can. So there are two general rules: ( 1) If an ion derives from a strong acid or base, it will not affect the acidity of the solution. ( 2) If an ion derives from a weak acid, it will make the solution basic; if an ion derives from a weak base, it will make the solution acidic.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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The molecule NH 3 is a weak base, and it will form when it can, just like a weak acid will form when it can. So there are two general rules: ( 1) If an ion derives from a strong acid or base, it will not affect the acidity of the solution. ( 2) If an ion derives from a weak acid, it will make the solution basic; if an ion derives from a weak base, it will make the solution acidic. Example 8
Identify each salt as acidic, basic, or neutral. KCl
KNO 2
NH 4 Br
Solution
The ions from KCl derive from a strong acid (HCl) and a strong base (KOH). Therefore, neither ion will affect the acidity of the solution, so KCl is a neutral salt. Although the K + ion derives from a strong base (KOH), the NO 2− ion derives from a weak acid (HNO 2 ). Therefore the solution will be basic, and KNO 2 is a basic salt.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
|
Example 8
Identify each salt as acidic, basic, or neutral. KCl
KNO 2
NH 4 Br
Solution
The ions from KCl derive from a strong acid (HCl) and a strong base (KOH). Therefore, neither ion will affect the acidity of the solution, so KCl is a neutral salt. Although the K + ion derives from a strong base (KOH), the NO 2− ion derives from a weak acid (HNO 2 ). Therefore the solution will be basic, and KNO 2 is a basic salt. Although the Br − ions derive from a strong acid (HBr), the NH 4+ ion derives from a weak base (NH 3 ), so the solution will be acidic, and NH 4 Br is an acidic salt. Test Yourself
Identify each salt as acidic, basic, or neutral. (C 5 H 5 NH)Cl
Na 2 SO 3
Answers
acidic
basic
Some salts are composed of ions that come from both weak acids and weak bases. The overall effect on an aqueous solution depends on which ion exerts more influence on the overall acidity. We will not consider such salts here.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
|
Although the Br − ions derive from a strong acid (HBr), the NH 4+ ion derives from a weak base (NH 3 ), so the solution will be acidic, and NH 4 Br is an acidic salt. Test Yourself
Identify each salt as acidic, basic, or neutral. (C 5 H 5 NH)Cl
Na 2 SO 3
Answers
acidic
basic
Some salts are composed of ions that come from both weak acids and weak bases. The overall effect on an aqueous solution depends on which ion exerts more influence on the overall acidity. We will not consider such salts here. Key Takeaways
Strong acids and bases are 100% ionized in aqueous solution. Weak acids and bases are less than 100% ionized in aqueous solution. Salts of weak acids or bases can affect the acidity or basicity of their aqueous solutions. Exercises
Differentiate between a strong acid and a weak acid. Differentiate between a strong base and a weak base.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
|
Key Takeaways
Strong acids and bases are 100% ionized in aqueous solution. Weak acids and bases are less than 100% ionized in aqueous solution. Salts of weak acids or bases can affect the acidity or basicity of their aqueous solutions. Exercises
Differentiate between a strong acid and a weak acid. Differentiate between a strong base and a weak base. Identify each as a strong acid or a weak acid. Assume aqueous solutions. HF
HCl
HC 2 O 4
Identify each as a strong base or a weak base. Assume aqueous solutions. NaOH
Al (OH) 3
C 4 H 9 NH 2
Write a chemical equation for the ionization of each acid and indicate whether it proceeds 100% to products or not.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
|
Identify each as a strong acid or a weak acid. Assume aqueous solutions. HF
HCl
HC 2 O 4
Identify each as a strong base or a weak base. Assume aqueous solutions. NaOH
Al (OH) 3
C 4 H 9 NH 2
Write a chemical equation for the ionization of each acid and indicate whether it proceeds 100% to products or not. HNO 3
HNO 2
HI 3
Write a chemical equation for the ionization of each base and indicate whether it proceeds 100% to products or not. NH 3
(CH 3) 3 N
Mg (OH) 2
Write the balanced chemical equation for the reaction of each acid and base pair. HCl + C 5 H 5 N
H 2 C 2 O 4 + NH 3
HNO 2 + C 7 H 9 N
Write the balanced chemical equation for the reaction of each acid and base pair. H 3 C 5 H 5 O 7 + Mg (OH) 2
HC 3 H 3 O 3 + (CH 3) 3 N
HBr + Fe (OH) 3
Identify each salt as neutral, acidic, or basic. NaBr
Fe (NO 3) 2
Fe (NO 3) 3
Identify each salt as neutral, acidic, or basic.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
|
HNO 3
HNO 2
HI 3
Write a chemical equation for the ionization of each base and indicate whether it proceeds 100% to products or not. NH 3
(CH 3) 3 N
Mg (OH) 2
Write the balanced chemical equation for the reaction of each acid and base pair. HCl + C 5 H 5 N
H 2 C 2 O 4 + NH 3
HNO 2 + C 7 H 9 N
Write the balanced chemical equation for the reaction of each acid and base pair. H 3 C 5 H 5 O 7 + Mg (OH) 2
HC 3 H 3 O 3 + (CH 3) 3 N
HBr + Fe (OH) 3
Identify each salt as neutral, acidic, or basic. NaBr
Fe (NO 3) 2
Fe (NO 3) 3
Identify each salt as neutral, acidic, or basic. NH 4 I
C 2 H 5 NH 3 Cl
KI
Identify each salt as neutral, acidic, or basic. NaNO 2
NaNO 3
NH 4 NO 3
Identify each salt as neutral, acidic, or basic. KC 2 H 3 O 2
KHSO 4
KClO 3
Write the hydrolysis reaction that occurs, if any, when each salt dissolves in water. K 2 SO 3
KI
NH 4 ClO 3
Write the hydrolysis reaction that occurs, if any, when each salt dissolves in water. NaNO 3
CaC 2 O 4
C 5 H 5 NHCl
When NH 4 NO 2 dissolves in H 2 O, both ions hydrolyze.
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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NH 4 I
C 2 H 5 NH 3 Cl
KI
Identify each salt as neutral, acidic, or basic. NaNO 2
NaNO 3
NH 4 NO 3
Identify each salt as neutral, acidic, or basic. KC 2 H 3 O 2
KHSO 4
KClO 3
Write the hydrolysis reaction that occurs, if any, when each salt dissolves in water. K 2 SO 3
KI
NH 4 ClO 3
Write the hydrolysis reaction that occurs, if any, when each salt dissolves in water. NaNO 3
CaC 2 O 4
C 5 H 5 NHCl
When NH 4 NO 2 dissolves in H 2 O, both ions hydrolyze. Write chemical equations for both reactions. Can you tell if the solution will be acidic or basic overall? When pyridinium acetate (C 5 H 5 NHC 2 H 3 O 2) dissolves in H 2 O, both ions hydrolyze. Write chemical equations for both reactions. Can you tell if the solution will be acidic or basic overall?
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
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Write chemical equations for both reactions. Can you tell if the solution will be acidic or basic overall? When pyridinium acetate (C 5 H 5 NHC 2 H 3 O 2) dissolves in H 2 O, both ions hydrolyze. Write chemical equations for both reactions. Can you tell if the solution will be acidic or basic overall? A lab technician mixes a solution of 0.015 M Mg (OH) 2. Is the resulting OH − concentration greater than, equal to, or less than 0.015 M? Explain your answer. A lab technician mixes a solution of 0.55 M HNO 3. Is the resulting H + concentration greater than, equal to, or less than 0.55 M?
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Strong and Weak Acids and Bases and Their Salts
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12.4
Strong and Weak Acids and Bases and Their Salts
12.4 Strong and Weak Acids and Bases and Their Salts
Learning Objectives
Example 6
Example 7
Example 8
Key Takeaways
Exercises
Answers
|
A lab technician mixes a solution of 0.015 M Mg (OH) 2. Is the resulting OH − concentration greater than, equal to, or less than 0.015 M? Explain your answer. A lab technician mixes a solution of 0.55 M HNO 3. Is the resulting H + concentration greater than, equal to, or less than 0.55 M? Explain your answer. Answers
A strong acid is 100% ionized in aqueous solution, whereas a weak acid is not 100% ioniz
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Define Le Chatelier’s principle. Predict the direction of shift for an equilibrium under stress. Once equilibrium is established, the reaction is over, right? Not exactly. An experimenter has some ability to affect the equilibrium. Chemical equilibria can be shifted by changing the conditions that the system experiences. We say that we “stress” the equilibrium. When we stress the equilibrium, the chemical reaction is no longer at equilibrium, and the reaction starts to move back toward equilibrium in such a way as to decrease the stress.
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
Not exactly. An experimenter has some ability to affect the equilibrium. Chemical equilibria can be shifted by changing the conditions that the system experiences. We say that we “stress” the equilibrium. When we stress the equilibrium, the chemical reaction is no longer at equilibrium, and the reaction starts to move back toward equilibrium in such a way as to decrease the stress. The formal statement is called Le Chatelier’s principle
If an equilibrium is stressed, then the reaction shifts to reduce the stress. : If an equilibrium is stressed, then the reaction shifts to reduce the stress. There are several ways to stress an equilibrium. One way is to add or remove a product or a reactant in a chemical reaction at equilibrium.
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
The formal statement is called Le Chatelier’s principle
If an equilibrium is stressed, then the reaction shifts to reduce the stress. : If an equilibrium is stressed, then the reaction shifts to reduce the stress. There are several ways to stress an equilibrium. One way is to add or remove a product or a reactant in a chemical reaction at equilibrium. When additional reactant is added, the equilibrium shifts to reduce this stress: it makes more product. When additional product is added, the equilibrium shifts to reactants to reduce the stress. If reactant or product is removed, the equilibrium shifts to make more reactant or product, respectively, to make up for the loss. Example 6
Given this reaction at equilibrium:
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Shifting Equilibria: Le Chatelier’s Principle
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
When additional reactant is added, the equilibrium shifts to reduce this stress: it makes more product. When additional product is added, the equilibrium shifts to reactants to reduce the stress. If reactant or product is removed, the equilibrium shifts to make more reactant or product, respectively, to make up for the loss. Example 6
Given this reaction at equilibrium: N 2 + 3H 2 ⇄ 2 NH 3
In which direction—toward reactants or toward products—does the reaction shift if the equilibrium is stressed by each change? H 2 is added. NH 3 is added. NH 3 is removed. Solution
If H 2 is added, there is now more reactant, so the reaction will shift toward products to reduce the added H 2.
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Shifting Equilibria: Le Chatelier’s Principle
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
N 2 + 3H 2 ⇄ 2 NH 3
In which direction—toward reactants or toward products—does the reaction shift if the equilibrium is stressed by each change? H 2 is added. NH 3 is added. NH 3 is removed. Solution
If H 2 is added, there is now more reactant, so the reaction will shift toward products to reduce the added H 2. If NH 3 is added, there is now more product, so the reaction will shift toward reactants to reduce the added NH 3. If NH 3 is removed, there is now less product, so the reaction will shift toward products to replace the product removed. Test Yourself
Given this reaction at equilibrium: CO (g) + Br 2 (g) ⇄ COBr 2 (g)
In which direction—toward reactants or toward products—does the reaction shift if the equilibrium is stressed by each change? Br 2 is removed.
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Shifting Equilibria: Le Chatelier’s Principle
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
If NH 3 is added, there is now more product, so the reaction will shift toward reactants to reduce the added NH 3. If NH 3 is removed, there is now less product, so the reaction will shift toward products to replace the product removed. Test Yourself
Given this reaction at equilibrium: CO (g) + Br 2 (g) ⇄ COBr 2 (g)
In which direction—toward reactants or toward products—does the reaction shift if the equilibrium is stressed by each change? Br 2 is removed. COBr 2 is added. Answers
toward reactants
toward reactants
It is worth noting that when reactants or products are added or removed, the value of the K eq does not change. The chemical reaction simply shifts, in a predictable fashion, to reestablish concentrations so that the Keq expression reverts to the correct value. How does an equilibrium react to a change in pressure? Pressure changes do not markedly affect the solid or liquid phases.
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
COBr 2 is added. Answers
toward reactants
toward reactants
It is worth noting that when reactants or products are added or removed, the value of the K eq does not change. The chemical reaction simply shifts, in a predictable fashion, to reestablish concentrations so that the Keq expression reverts to the correct value. How does an equilibrium react to a change in pressure? Pressure changes do not markedly affect the solid or liquid phases. However, pressure strongly impacts the gas phase. Le Chatelier’s principle implies that a pressure increase shifts an equilibrium to the side of the reaction with the fewer number of moles of gas, while a pressure decrease shifts an equilibrium to the side of the reaction with the greater number of moles of gas. If the number of moles of gas is the same on both sides of the reaction, pressure has no effect. Example 7
What is the effect on this equilibrium if pressure is increased? N 2 (g) + 3H 2 (g) ⇄ 2 NH 3 (g)
Solution
According to Le Chatelier’s principle, if pressure is increased, then the equilibrium shifts to the side with the fewer number of moles of gas.
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Shifting Equilibria: Le Chatelier’s Principle
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
However, pressure strongly impacts the gas phase. Le Chatelier’s principle implies that a pressure increase shifts an equilibrium to the side of the reaction with the fewer number of moles of gas, while a pressure decrease shifts an equilibrium to the side of the reaction with the greater number of moles of gas. If the number of moles of gas is the same on both sides of the reaction, pressure has no effect. Example 7
What is the effect on this equilibrium if pressure is increased? N 2 (g) + 3H 2 (g) ⇄ 2 NH 3 (g)
Solution
According to Le Chatelier’s principle, if pressure is increased, then the equilibrium shifts to the side with the fewer number of moles of gas. This particular reaction shows a total of 4 mol of gas as reactants and 2 mol of gas as products, so the reaction shifts toward the products side. Test Yourself
What is the effect on this equilibrium if pressure is decreased? 3O 2 (g) ⇄ 2O 3 (g)
Answer
Reaction shifts toward reactants. What is the effect of temperature changes on an equilibrium? It depends on whether the reaction is endothermic or exothermic.
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Shifting Equilibria: Le Chatelier’s Principle
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
This particular reaction shows a total of 4 mol of gas as reactants and 2 mol of gas as products, so the reaction shifts toward the products side. Test Yourself
What is the effect on this equilibrium if pressure is decreased? 3O 2 (g) ⇄ 2O 3 (g)
Answer
Reaction shifts toward reactants. What is the effect of temperature changes on an equilibrium? It depends on whether the reaction is endothermic or exothermic. Recall that endothermic means that energy is absorbed by a chemical reaction, while exothermic means that energy is given off by the reaction. As such, energy can be thought of as a reactant or a product, respectively, of a reaction: endothermic: energy + reactants → products exothermic: reactants → products + energy
Because temperature is a measure of the energy of the system, increasing temperature can be thought of as adding energy.
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
Recall that endothermic means that energy is absorbed by a chemical reaction, while exothermic means that energy is given off by the reaction. As such, energy can be thought of as a reactant or a product, respectively, of a reaction: endothermic: energy + reactants → products exothermic: reactants → products + energy
Because temperature is a measure of the energy of the system, increasing temperature can be thought of as adding energy. The reaction will react as if a reactant or a product is being added and will act accordingly by shifting to the other side. For example, if the temperature is increased for an endothermic reaction, essentially a reactant is being added, so the equilibrium shifts toward products. Decreasing the temperature is equivalent to decreasing a reactant (for endothermic reactions) or a product (for exothermic reactions), and the equilibrium shifts accordingly. Example 8
Predict the effect of increasing the temperature on this equilibrium. PCl 3 + Cl 2 ⇄ PCl 5 + 60 kJ
Solution
Because energy is listed as a product, it is being produced, so the reaction is exothermic.
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
The reaction will react as if a reactant or a product is being added and will act accordingly by shifting to the other side. For example, if the temperature is increased for an endothermic reaction, essentially a reactant is being added, so the equilibrium shifts toward products. Decreasing the temperature is equivalent to decreasing a reactant (for endothermic reactions) or a product (for exothermic reactions), and the equilibrium shifts accordingly. Example 8
Predict the effect of increasing the temperature on this equilibrium. PCl 3 + Cl 2 ⇄ PCl 5 + 60 kJ
Solution
Because energy is listed as a product, it is being produced, so the reaction is exothermic. If the temperature is increasing, a product is being added to the equilibrium, so the equilibrium shifts to minimize the addition of extra product: it shifts back toward reactants. Test Yourself
Predict the effect of decreasing the temperature on this equilibrium. N 2 O 4 + 57 kJ ⇄ 2NO 2
Answer
Equilibrium shifts toward reactants. In the case of temperature, the value of the equilibrium has changed because the Keq is dependent on temperature.
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
If the temperature is increasing, a product is being added to the equilibrium, so the equilibrium shifts to minimize the addition of extra product: it shifts back toward reactants. Test Yourself
Predict the effect of decreasing the temperature on this equilibrium. N 2 O 4 + 57 kJ ⇄ 2NO 2
Answer
Equilibrium shifts toward reactants. In the case of temperature, the value of the equilibrium has changed because the Keq is dependent on temperature. That is why equilibria shift with changes in temperature. A catalyst
A substance that increases the speed of a reaction. is a substance that increases the speed of a reaction. Overall, a catalyst is not a reactant and is not used up, but it still affects how fast a reaction proceeds. However, a catalyst does not affect the extent or position of a reaction at equilibrium.
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
That is why equilibria shift with changes in temperature. A catalyst
A substance that increases the speed of a reaction. is a substance that increases the speed of a reaction. Overall, a catalyst is not a reactant and is not used up, but it still affects how fast a reaction proceeds. However, a catalyst does not affect the extent or position of a reaction at equilibrium. It helps a reaction achieve equilibrium faster. Chemistry Is Everywhere: Equilibria in the Garden
Hydrangeas are common flowering plants around the world. Although many hydrangeas are white, there is one common species ( Hydrangea macrophylla) whose flowers can be either red or blue, as shown in the accompanying figure. How is it that a plant can have different colored flowers like this?
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
It helps a reaction achieve equilibrium faster. Chemistry Is Everywhere: Equilibria in the Garden
Hydrangeas are common flowering plants around the world. Although many hydrangeas are white, there is one common species ( Hydrangea macrophylla) whose flowers can be either red or blue, as shown in the accompanying figure. How is it that a plant can have different colored flowers like this? Figure 13.1 Garden Equilibria
This species of hydrangea has flowers that can be either red or blue. Why the color difference? © Thinkstock
Interestingly, the color of the flowers is due to the acidity of the soil that the hydrangea is planted in. An astute gardener can adjust the pH of the soil and actually change the color of the flowers. However, it is not the H + or OH − ions that affect the color of the flowers.
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
Figure 13.1 Garden Equilibria
This species of hydrangea has flowers that can be either red or blue. Why the color difference? © Thinkstock
Interestingly, the color of the flowers is due to the acidity of the soil that the hydrangea is planted in. An astute gardener can adjust the pH of the soil and actually change the color of the flowers. However, it is not the H + or OH − ions that affect the color of the flowers. Rather, it is the presence of aluminum that causes the color change. The solubility of aluminum in soil—and thus the ability of plants to absorb it—is dependent on the acidity of the soil. If the soil is relatively acidic, the aluminum is more soluble, and plants can absorb it more easily. Under these conditions, hydrangea flowers are blue as Al ions interact with anthocyanin pigments in the plant. In more basic soils, aluminum is less soluble, and under these conditions the hydrangea flowers are red.
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
Rather, it is the presence of aluminum that causes the color change. The solubility of aluminum in soil—and thus the ability of plants to absorb it—is dependent on the acidity of the soil. If the soil is relatively acidic, the aluminum is more soluble, and plants can absorb it more easily. Under these conditions, hydrangea flowers are blue as Al ions interact with anthocyanin pigments in the plant. In more basic soils, aluminum is less soluble, and under these conditions the hydrangea flowers are red. Gardeners who change the pH of their soils to change the color of their hydrangea flowers are therefore employing Le Chatelier’s principle: the amount of acid in the soil changes the equilibrium of aluminum solubility, which in turn affects the color of the flowers. Key Takeaways
Le Chatelier’s principle addresses how an equilibrium shifts when the conditions of an equilibrium are changed. The direction of shift can be predicted for changes in concentrations, temperature, or pressure. Catalysts do not affect the position of an equilibrium;
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
Gardeners who change the pH of their soils to change the color of their hydrangea flowers are therefore employing Le Chatelier’s principle: the amount of acid in the soil changes the equilibrium of aluminum solubility, which in turn affects the color of the flowers. Key Takeaways
Le Chatelier’s principle addresses how an equilibrium shifts when the conditions of an equilibrium are changed. The direction of shift can be predicted for changes in concentrations, temperature, or pressure. Catalysts do not affect the position of an equilibrium; they help reactions achieve equilibrium faster. Exercises
Define Le Chatelier’s principle. What is meant by a stress? What are some of the ways an equilibrium can be stressed? Given this equilibrium, predict the direction of shift for each stress.
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
|
they help reactions achieve equilibrium faster. Exercises
Define Le Chatelier’s principle. What is meant by a stress? What are some of the ways an equilibrium can be stressed? Given this equilibrium, predict the direction of shift for each stress. H 2 (g) + I 2 (s) + 53 kJ ⇄ 2HI (g)
decreased temperature
increased pressure
removal of HI
Given this equilibrium, predict the direction of shift for each stress. H 2 (g) + F 2 (g) ⇄ 2HF (g) + 546 kJ
increased temperature
addition of H 2
decreased pressure
Given this equilibrium, predict the direction of shift for each stress. 2SO 2 (g) + O 2 (g) ⇄ 2SO 3 (g) + 196 kJ
removal of SO 3
addition of O 2
decreased temperature
Given this equilibrium, predict the direction of shift for each stress listed. CO 2 (g) + C (s) + 171 kJ ⇄ 2CO (g)
addition of CO
increased pressure
addition of a catalyst
The synthesis of NH 3 uses this chemical reaction. N 2 (g) + 3H 2 (g) ⇄ 2 NH 3 (g) + 92 kJ
Identify three stresses that can be imposed on the equilibrium to maximize the amount of NH 3.
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13.3
Shifting Equilibria: Le Chatelier’s Principle
13.3 Shifting Equilibria: Le Chatelier’s Principle
Learning Objectives
Example 6
Example 7
Example 8
Chemistry Is Everywhere: Equilibria in the Garden
Key Takeaways
Exercises
Answers
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H 2 (g) + I 2 (s) + 53 kJ ⇄ 2HI (g)
decreased temperature
increased pressure
removal of HI
Given this equilibrium, predict the direction of shift for each stress. H 2 (g) + F 2 (g) ⇄ 2HF (g) + 546 kJ
increased temperature
addition of H 2
decreased pressure
Given this equilibrium, predict the direction of shift for each stress. 2SO 2 (g) + O 2 (g) ⇄ 2SO 3 (g) + 196 kJ
removal of SO 3
addition of O 2
decreased temperature
Given this equilibrium, predict the direction of shift for each stress listed. CO 2 (g) + C (s) + 171 kJ ⇄ 2CO (g)
addition of CO
increased pressure
addition of a catalyst
The synthesis of NH 3 uses this chemical reaction. N 2 (g) + 3H 2 (g) ⇄ 2 NH 3 (g) + 92 kJ
Identify three stresses that can be imposed on the equilibrium to maximize the amount of NH 3. The synthesis of CaCO 3 uses this chemical reaction. CaO (s) + CO 2 (g) ⇄ CaCO 3 (s) + 180 kJ
Identify three stresses that can be imposed on the equilibrium to maximize the amount of CaCO 3. Answers
When an equilibrium is stressed, the equilibrium shifts to minimize that stress. toward reactants
toward reactants
toward products
toward products
toward products
toward products
increased pressure, decreased temperature, removal of NH 3
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
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Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Identify the aldehyde, ketone, acid, ester, and ether functional groups. There are other functional groups that contain O atoms. Before we introduce them, we define the carbonyl group
A functional group formed when an O atom and a C atom are joined with a double bond. , which is formed when an O atom and a C atom are joined by a double bond: The other two bonds on the C atom are attached to other atoms. It is the identities of these other atoms that define what specific type of compound an organic molecule is. If one bond of the carbonyl group is made to an H atom, then the molecule is classified as an aldehyde
A compound that has a carbonyl functional group at the end of a chain of C atoms. . ( If there are two H atoms, there is only 1 C atom.) When naming aldehydes, the main chain of C atoms must include the carbon in the carbonyl group, which is numbered as position 1 in the carbon chain.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
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It is the identities of these other atoms that define what specific type of compound an organic molecule is. If one bond of the carbonyl group is made to an H atom, then the molecule is classified as an aldehyde
A compound that has a carbonyl functional group at the end of a chain of C atoms. . ( If there are two H atoms, there is only 1 C atom.) When naming aldehydes, the main chain of C atoms must include the carbon in the carbonyl group, which is numbered as position 1 in the carbon chain. The parent name of the hydrocarbon is used, but the suffix - al is appended. ( Do not confuse - al with - ol, which is the suffix used for alcohols.) So we have
Methanal has a common name with which you may be familiar: formaldehyde. The main thing to note about aldehydes is that the carbonyl group is at the end of a carbon chain.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
The parent name of the hydrocarbon is used, but the suffix - al is appended. ( Do not confuse - al with - ol, which is the suffix used for alcohols.) So we have
Methanal has a common name with which you may be familiar: formaldehyde. The main thing to note about aldehydes is that the carbonyl group is at the end of a carbon chain. A carbonyl group in the middle of a carbon chain implies that both remaining bonds of the carbonyl group are made to C atoms. This type of molecule is called a ketone
A compound that has a carbonyl group in the middle of a carbon chain. . Despite the fact that aldehydes and ketones have the same carbonyl group, they have different chemical and physical properties and are properly grouped as two different types of compounds. The smallest ketone has three C atoms in it.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
A carbonyl group in the middle of a carbon chain implies that both remaining bonds of the carbonyl group are made to C atoms. This type of molecule is called a ketone
A compound that has a carbonyl group in the middle of a carbon chain. . Despite the fact that aldehydes and ketones have the same carbonyl group, they have different chemical and physical properties and are properly grouped as two different types of compounds. The smallest ketone has three C atoms in it. When naming a ketone, we take the name of the parent hydrocarbon and change the suffix to - one: The common name for propanone is acetone. With larger ketones, we must use a number to indicate the position of the carbonyl group, much like a number is used with alkenes and alkynes: There is another way to name ketones: name the alkyl groups that are attached to the carbonyl group and add the word ketone to the name.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
When naming a ketone, we take the name of the parent hydrocarbon and change the suffix to - one: The common name for propanone is acetone. With larger ketones, we must use a number to indicate the position of the carbonyl group, much like a number is used with alkenes and alkynes: There is another way to name ketones: name the alkyl groups that are attached to the carbonyl group and add the word ketone to the name. So propanone can also be called dimethyl ketone, while 2-butanone is called methyl ethyl ketone. Example 9
Draw the structure of 2-pentanone. Solution
This molecule has five C atoms in a chain, with the carbonyl group on the second C atom. Its structure is as follows: Test Yourself
Draw the structure of methyl butyl ketone.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
So propanone can also be called dimethyl ketone, while 2-butanone is called methyl ethyl ketone. Example 9
Draw the structure of 2-pentanone. Solution
This molecule has five C atoms in a chain, with the carbonyl group on the second C atom. Its structure is as follows: Test Yourself
Draw the structure of methyl butyl ketone. Answer
The combination of a carbonyl functional group and an OH group makes the carboxyl group
A functional group composed of a carbonyl group and an OH group. . Molecules with a carboxyl group are called carboxylic acids
A molecule with a carboxyl group. . As with aldehydes, the functional group in carboxylic acids is at the end of a carbon chain.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
Answer
The combination of a carbonyl functional group and an OH group makes the carboxyl group
A functional group composed of a carbonyl group and an OH group. . Molecules with a carboxyl group are called carboxylic acids
A molecule with a carboxyl group. . As with aldehydes, the functional group in carboxylic acids is at the end of a carbon chain. Also as with aldehydes, the C atom in the functional group is counted as one of the C atoms that defines the parent hydrocarbon name. To name carboxylic acids, the parent name of the hydrocarbon is used, but the suffix - oic acid is added: Methanoic acid and ethanoic acid are also called formic acid and acetic acid, respectively. Formic acid is the compound that makes certain ant bites sting, while acetic acid is the active substance in vinegar. How acidic are carboxylic acids?
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
Also as with aldehydes, the C atom in the functional group is counted as one of the C atoms that defines the parent hydrocarbon name. To name carboxylic acids, the parent name of the hydrocarbon is used, but the suffix - oic acid is added: Methanoic acid and ethanoic acid are also called formic acid and acetic acid, respectively. Formic acid is the compound that makes certain ant bites sting, while acetic acid is the active substance in vinegar. How acidic are carboxylic acids? It turns out that they are not very acidic. No carboxylic acid is on the list of strong acids ( Table 12.2 "Strong Acids and Bases" ). ( For more information about strong acids, see Chapter 12 "Acids and Bases", Section 12.4 "Strong and Weak Acids and Bases and Their Salts" .) This means that all carboxylic acids are weak acids. A 1 M solution of formic acid is only about 1.3% dissociated into H + ions and formate ions, while a similar solution of acetic acid is ionized by about only 0.4%.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
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It turns out that they are not very acidic. No carboxylic acid is on the list of strong acids ( Table 12.2 "Strong Acids and Bases" ). ( For more information about strong acids, see Chapter 12 "Acids and Bases", Section 12.4 "Strong and Weak Acids and Bases and Their Salts" .) This means that all carboxylic acids are weak acids. A 1 M solution of formic acid is only about 1.3% dissociated into H + ions and formate ions, while a similar solution of acetic acid is ionized by about only 0.4%. Some carboxylic acids are stronger—for example, trichloroacetic acid is about 45% dissociated in aqueous solution. But no carboxylic acid approaches the 100% dissociation amount required by the definition of a strong acid. As their name suggests, however, carboxylic acids do act like acids in the presence of bases. The H atom in the carboxyl group comes off as the H + ion, leaving a carboxylate
A negatively charged ion derived from a carboxylic acid. anion:
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
Some carboxylic acids are stronger—for example, trichloroacetic acid is about 45% dissociated in aqueous solution. But no carboxylic acid approaches the 100% dissociation amount required by the definition of a strong acid. As their name suggests, however, carboxylic acids do act like acids in the presence of bases. The H atom in the carboxyl group comes off as the H + ion, leaving a carboxylate
A negatively charged ion derived from a carboxylic acid. anion: Carboxylate ions are named from the acid name: the - oic acid is replaced with - oate to name the ion. Example 10
Complete the chemical reaction. Can you name the carboxylate ion formed? Solution
The OH – ion removes the H atom that is part of the carboxyl group:
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
Carboxylate ions are named from the acid name: the - oic acid is replaced with - oate to name the ion. Example 10
Complete the chemical reaction. Can you name the carboxylate ion formed? Solution
The OH – ion removes the H atom that is part of the carboxyl group: The carboxylate ion, which has the condensed structural formula CH 3 CO 2−, is the ethanoate ion, but it is commonly called the acetate ion. Test Yourself
Complete the chemical reaction. Can you name the carboxylate ion formed? Answer
The anion is the methanoate ion, which is commonly called the formate ion. One reaction to consider is that of a carboxylic acid and an alcohol.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
The carboxylate ion, which has the condensed structural formula CH 3 CO 2−, is the ethanoate ion, but it is commonly called the acetate ion. Test Yourself
Complete the chemical reaction. Can you name the carboxylate ion formed? Answer
The anion is the methanoate ion, which is commonly called the formate ion. One reaction to consider is that of a carboxylic acid and an alcohol. When combined under the proper conditions, a water molecule will be removed, and the remaining pieces will combine to form a new functional group—the ester
A functional group made by combining a carboxylic acid with an alcohol. functional group: Note how the acid molecule contributes one alkyl side (represented by R), while the alcohol contributes the other side (represented by R′). Esters are named using the alkyl group name from the alcohol plus the carboxylate name from the acid—for example, the molecule
is called methyl propanoate. Chemistry Is Everywhere:
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
When combined under the proper conditions, a water molecule will be removed, and the remaining pieces will combine to form a new functional group—the ester
A functional group made by combining a carboxylic acid with an alcohol. functional group: Note how the acid molecule contributes one alkyl side (represented by R), while the alcohol contributes the other side (represented by R′). Esters are named using the alkyl group name from the alcohol plus the carboxylate name from the acid—for example, the molecule
is called methyl propanoate. Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Esters are very interesting compounds, in part because many have very pleasant odors and flavors. ( Remember, never taste anything in the chemistry lab!) Many esters occur naturally and contribute to the odor of flowers and the taste of fruits. Other esters are synthesized industrially and are added to food products to improve their smell or taste; it is likely that if you eat a product whose ingredients include artificial flavorings, those flavorings are esters.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
Esters, Fragrances, and Flavorings
Esters are very interesting compounds, in part because many have very pleasant odors and flavors. ( Remember, never taste anything in the chemistry lab!) Many esters occur naturally and contribute to the odor of flowers and the taste of fruits. Other esters are synthesized industrially and are added to food products to improve their smell or taste; it is likely that if you eat a product whose ingredients include artificial flavorings, those flavorings are esters. Here are some esters and their uses, thanks to their odors, flavors, or both: Ester
Tastes/Smells Like
Ester
Tastes/Smells Like
allyl hexanoate
pineapple
isobutyl formate
raspberry
benzyl acetate
pear
isobutyl acetate
pear
butyl butanoate
pineapple
methyl phenylacetate
honey
ethyl butanoate
banana
nonyl caprylate
orange
ethyl hexanoate
pineapple
pentyl acetate
apple
ethyl heptanoate
apricot
propyl ethanoate
pear
ethyl pentanoate
apple
propyl isobutyrate
rum
Finally, the ether
A functional group that has an O atom attached to two organic groups. functional group is an O atom that is bonded to two organic groups: R—O—R′
The two R groups may be the same or different. Naming ethers is like the alternate way of naming ketones.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
Here are some esters and their uses, thanks to their odors, flavors, or both: Ester
Tastes/Smells Like
Ester
Tastes/Smells Like
allyl hexanoate
pineapple
isobutyl formate
raspberry
benzyl acetate
pear
isobutyl acetate
pear
butyl butanoate
pineapple
methyl phenylacetate
honey
ethyl butanoate
banana
nonyl caprylate
orange
ethyl hexanoate
pineapple
pentyl acetate
apple
ethyl heptanoate
apricot
propyl ethanoate
pear
ethyl pentanoate
apple
propyl isobutyrate
rum
Finally, the ether
A functional group that has an O atom attached to two organic groups. functional group is an O atom that is bonded to two organic groups: R—O—R′
The two R groups may be the same or different. Naming ethers is like the alternate way of naming ketones. In this case, the R groups are named sequentially, and the word ether is appended. The molecule
CH3OCH3
is dimethyl ether, while
CH3OCH2CH3
is methyl ethyl ether. Diethyl ether, another ether, was once used as an anesthetic, but its flammability and toxicity caused it to fall out of favor. Smaller ether molecules that are liquids at room temperature are common solvents for organic chemical reactions. Key Takeaway
Aldehydes, ketones, carboxylic acids, esters, and ethers have oxygen-containing functional groups.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
In this case, the R groups are named sequentially, and the word ether is appended. The molecule
CH3OCH3
is dimethyl ether, while
CH3OCH2CH3
is methyl ethyl ether. Diethyl ether, another ether, was once used as an anesthetic, but its flammability and toxicity caused it to fall out of favor. Smaller ether molecules that are liquids at room temperature are common solvents for organic chemical reactions. Key Takeaway
Aldehydes, ketones, carboxylic acids, esters, and ethers have oxygen-containing functional groups. Exercises
Name a similarity between the functional groups found in aldehydes and ketones. Can you name a difference between them? Explain how a carboxylic acid is used to make an ester. Name each molecule. Name each molecule.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
Exercises
Name a similarity between the functional groups found in aldehydes and ketones. Can you name a difference between them? Explain how a carboxylic acid is used to make an ester. Name each molecule. Name each molecule. Name each molecule. Name each molecule. Name this molecule. Name this molecule. Give an alternate but acceptable name to the molecule in Exercise 3b.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
Name each molecule. Name each molecule. Name this molecule. Name this molecule. Give an alternate but acceptable name to the molecule in Exercise 3b. Give an alternate but acceptable name to the molecule in Exercise 4b. Complete this chemical reaction. Complete this chemical reaction. The drug known as aspirin has this molecular structure: Identify the functional group (s) in this molecule.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
Give an alternate but acceptable name to the molecule in Exercise 4b. Complete this chemical reaction. Complete this chemical reaction. The drug known as aspirin has this molecular structure: Identify the functional group (s) in this molecule. The drug known as naproxen sodium is the sodium salt of this molecule: (The extra H atoms are omitted for clarity.) Identify the functional group (s) in this molecule. Identify the ester made by reacting these molecules. Identify the ester made by reacting these molecules.
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16.4
Other Oxygen-Containing Functional Groups
16.4 Other Oxygen-Containing Functional Groups
Learning Objective
Example 9
Example 10
Chemistry Is Everywhere: Esters, Fragrances, and Flavorings
Key Takeaway
Exercises
Answers
|
The drug known as naproxen sodium is the sodium salt of this molecule: (The extra H atoms are omitted for clarity.) Identify the functional group (s) in this molecule. Identify the ester made by reacting these molecules. Identify the ester made by reacting these molecules. Answers
They both have a carbonyl group, but an aldehyde has the carbonyl group at the end of a carbon chain, and a ketone has the carbonyl group in the middle. propanal
2-butanone
3-methylbutanoic acid
ethyl propionate
ethyl propyl ether
ethyl methyl ketone
H 2 O + KCH 3 CH 2 CO 2
acid, ester, and aromatic (benzene ring)
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The Role of Human Resources
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Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
You have just been hired to work in the human resource department of a small company. You heard about the job through a conference you attended, put on by the Society for Human Resource Management (SHRM). Previously, the owner of the company, Jennifer, had been doing everything related to human resource management (HRM). You can tell she is a bit critical about paying a good salary for something she was able to juggle all on her own. On your first day, you meet the ten employees and spend several hours with the company owner, hoping to get a handle on which human resource processes are already set up. Shortly after the meeting begins, you see she has a completely different perspective of what HRM is, and you realize it will be your job to educate her on the value of a human resource manager. You look at it as a personal challenge—both to educate her and also to show her the value of this role in the organization. First, you tell her that HRM is a strategic process having to do with the staffing, compensation, retention, training, and employment law and policies side of the business. In other words, your job as human resources (HR) manager will be not only to write policy and procedures and to hire people (the administrative role) but also to use strategic plans to ensure the right people are hired and trained for the right job at the right time. For example, you ask her if she knows what the revenue will be in six months, and Jennifer answers, “Of course.
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The Role of Human Resources
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Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
Shortly after the meeting begins, you see she has a completely different perspective of what HRM is, and you realize it will be your job to educate her on the value of a human resource manager. You look at it as a personal challenge—both to educate her and also to show her the value of this role in the organization. First, you tell her that HRM is a strategic process having to do with the staffing, compensation, retention, training, and employment law and policies side of the business. In other words, your job as human resources (HR) manager will be not only to write policy and procedures and to hire people (the administrative role) but also to use strategic plans to ensure the right people are hired and trained for the right job at the right time. For example, you ask her if she knows what the revenue will be in six months, and Jennifer answers, “Of course. We expect it to increase by 20 percent.” You ask, “Have you thought about how many people you will need due to this increase?” Jennifer looks a bit sheepish and says, “No, I guess I haven’t gotten that far.” Then you ask her about the training programs the company offers, the software used to allow employees to access pay information online, and the compensation policies. She responds, “It looks like we have some work to do.
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The Role of Human Resources
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Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
We expect it to increase by 20 percent.” You ask, “Have you thought about how many people you will need due to this increase?” Jennifer looks a bit sheepish and says, “No, I guess I haven’t gotten that far.” Then you ask her about the training programs the company offers, the software used to allow employees to access pay information online, and the compensation policies. She responds, “It looks like we have some work to do. I didn’t know that human resources involved all of that.” You smile at her and start discussing some of the specifics of the business, so you can get started right away writing the strategic human resource management plan. The Role of Human Resources
(click to see video)
The author introduces the chapter defining the role of human resource management. 1.1 What Is Human Resources? Learning Objectives
Explain the role of HRM in organizations.
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The Role of Human Resources
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Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
I didn’t know that human resources involved all of that.” You smile at her and start discussing some of the specifics of the business, so you can get started right away writing the strategic human resource management plan. The Role of Human Resources
(click to see video)
The author introduces the chapter defining the role of human resource management. 1.1 What Is Human Resources? Learning Objectives
Explain the role of HRM in organizations. Define and discuss some of the major HRM activities. Every organization, large or small, uses a variety of capital
Capital includes cash, valuables, or goods used to generate income for a business. to make the business work. Capital includes cash, valuables, or goods used to generate income for a business. For example, a retail store uses registers and inventory, while a consulting firm may have proprietary software or buildings.
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The Role of Human Resources
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Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
Define and discuss some of the major HRM activities. Every organization, large or small, uses a variety of capital
Capital includes cash, valuables, or goods used to generate income for a business. to make the business work. Capital includes cash, valuables, or goods used to generate income for a business. For example, a retail store uses registers and inventory, while a consulting firm may have proprietary software or buildings. No matter the industry, all companies have one thing in common: they must have people to make their capital work for them. This will be our focus throughout the text: generation of revenue through the use of people’s skills and abilities. What Is HRM?
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The Role of Human Resources
|
Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
No matter the industry, all companies have one thing in common: they must have people to make their capital work for them. This will be our focus throughout the text: generation of revenue through the use of people’s skills and abilities. What Is HRM? Human resource management (HRM)
The process of employing people, training them, compensating them, developing policies relating to the workplace, and developing strategies to retain employees. is the process of employing people, training them, compensating them, developing policies relating to them, and developing strategies to retain them. As a field, HRM has undergone many changes over the last twenty years, giving it an even more important role in today’s organizations. In the past, HRM meant processing payroll, sending birthday gifts to employees, arranging company outings, and making sure forms were filled out correctly—in other words, more of an administrative role rather than a strategic role crucial to the success of the organization. Jack Welch, former CEO of General Electric and management guru, sums up the new role of HRM: “
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The Role of Human Resources
|
Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
Human resource management (HRM)
The process of employing people, training them, compensating them, developing policies relating to the workplace, and developing strategies to retain employees. is the process of employing people, training them, compensating them, developing policies relating to them, and developing strategies to retain them. As a field, HRM has undergone many changes over the last twenty years, giving it an even more important role in today’s organizations. In the past, HRM meant processing payroll, sending birthday gifts to employees, arranging company outings, and making sure forms were filled out correctly—in other words, more of an administrative role rather than a strategic role crucial to the success of the organization. Jack Welch, former CEO of General Electric and management guru, sums up the new role of HRM: “ Get out of the parties and birthdays and enrollment forms.… Remember, HR is important in good times, HR is defined in hard times.” Kristen B. Frasch, David Shadovitz, and Jared Shelly, “There’s No Whining in HR,” Human Resource Executive Online, June 30, 2009, accessed September 24, 2010, http://www.hreonline.com/HRE/story.jsp?storyId=227738167. It’s necessary to point out here, at the very beginning of this text, that every manager has some role relating to human resource management. Just because we do not have the title of HR manager doesn’t mean we won’t perform all or at least some of the HRM tasks.
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The Role of Human Resources
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Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
Get out of the parties and birthdays and enrollment forms.… Remember, HR is important in good times, HR is defined in hard times.” Kristen B. Frasch, David Shadovitz, and Jared Shelly, “There’s No Whining in HR,” Human Resource Executive Online, June 30, 2009, accessed September 24, 2010, http://www.hreonline.com/HRE/story.jsp?storyId=227738167. It’s necessary to point out here, at the very beginning of this text, that every manager has some role relating to human resource management. Just because we do not have the title of HR manager doesn’t mean we won’t perform all or at least some of the HRM tasks. For example, most managers deal with compensation, motivation, and retention of employees—making these aspects not only part of HRM but also part of management. As a result, this book is equally important to someone who wants to be an HR manager and to someone who will manage a business. Human Resource Recall
Have you ever had to work with a human resource department at your job? What was the interaction like? What was the department’s role in that specific organization?
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The Role of Human Resources
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Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
For example, most managers deal with compensation, motivation, and retention of employees—making these aspects not only part of HRM but also part of management. As a result, this book is equally important to someone who wants to be an HR manager and to someone who will manage a business. Human Resource Recall
Have you ever had to work with a human resource department at your job? What was the interaction like? What was the department’s role in that specific organization? The Role of HRM
Keep in mind that many functions of HRM are also tasks other department managers perform, which is what makes this information important, despite the career path taken. Most experts agree on seven main roles that HRM plays in organizations. These are described in the following sections. Staffing
You need people to perform tasks and get work done in the organization. Even with the most sophisticated machines, humans are still needed.
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The Role of Human Resources
|
Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
The Role of HRM
Keep in mind that many functions of HRM are also tasks other department managers perform, which is what makes this information important, despite the career path taken. Most experts agree on seven main roles that HRM plays in organizations. These are described in the following sections. Staffing
You need people to perform tasks and get work done in the organization. Even with the most sophisticated machines, humans are still needed. Because of this, one of the major tasks in HRM is staffing. Staffing
The entire hiring process from the first step of posting a job to the actual hiring of an employee. involves the entire hiring process from posting a job to negotiating a salary package. Within the staffing function, there are four main steps: Development of a staffing plan.
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The Role of Human Resources
|
Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
Because of this, one of the major tasks in HRM is staffing. Staffing
The entire hiring process from the first step of posting a job to the actual hiring of an employee. involves the entire hiring process from posting a job to negotiating a salary package. Within the staffing function, there are four main steps: Development of a staffing plan. This plan allows HRM to see how many people they should hire based on revenue expectations. Development of policies to encourage multiculturalism at work. Multiculturalism in the workplace is becoming more and more important, as we have many more people from a variety of backgrounds in the workforce. Recruitment. This involves finding people to fill the open positions.
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The Role of Human Resources
|
Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
This plan allows HRM to see how many people they should hire based on revenue expectations. Development of policies to encourage multiculturalism at work. Multiculturalism in the workplace is becoming more and more important, as we have many more people from a variety of backgrounds in the workforce. Recruitment. This involves finding people to fill the open positions. Selection. In this stage, people will be interviewed and selected, and a proper compensation package will be negotiated. This step is followed by training, retention, and motivation. Development of Workplace Policies
Every organization has policies to ensure fairness and continuity within the organization. One of the jobs of HRM is to develop the verbiage surrounding these policies.
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The Role of Human Resources
|
Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
Selection. In this stage, people will be interviewed and selected, and a proper compensation package will be negotiated. This step is followed by training, retention, and motivation. Development of Workplace Policies
Every organization has policies to ensure fairness and continuity within the organization. One of the jobs of HRM is to develop the verbiage surrounding these policies. In the development of policies, HRM, management, and executives are involved in the process. For example, the HRM professional will likely recognize the need for a policy or a change of policy, seek opinions on the policy, write the policy, and then communicate that policy to employees. It is key to note here that HR departments do not and cannot work alone. Everything they do needs to involve all other departments in the organization. Some examples of workplace policies might be the following:
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|
The Role of Human Resources
|
Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
In the development of policies, HRM, management, and executives are involved in the process. For example, the HRM professional will likely recognize the need for a policy or a change of policy, seek opinions on the policy, write the policy, and then communicate that policy to employees. It is key to note here that HR departments do not and cannot work alone. Everything they do needs to involve all other departments in the organization. Some examples of workplace policies might be the following: Discipline process policy
Vacation time policy
Dress code
Ethics policy
Internet usage policy
These topics are addressed further in Chapter 6 "Compensation and Benefits", Chapter 7 "Retention and Motivation", Chapter 8 "Training and Development", and Chapter 9 "Successful Employee Communication". Compensation and Benefits Administration
HRM professionals need to determine that compensation is fair, meets industry standards, and is high enough to entice people to work for the organization. Compensation
Anything the employee receives for his or her work. It can include pay, benefits, vacation time, and sick leave. includes anything the employee receives for his or her work.
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The Role of Human Resources
|
Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
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Discipline process policy
Vacation time policy
Dress code
Ethics policy
Internet usage policy
These topics are addressed further in Chapter 6 "Compensation and Benefits", Chapter 7 "Retention and Motivation", Chapter 8 "Training and Development", and Chapter 9 "Successful Employee Communication". Compensation and Benefits Administration
HRM professionals need to determine that compensation is fair, meets industry standards, and is high enough to entice people to work for the organization. Compensation
Anything the employee receives for his or her work. It can include pay, benefits, vacation time, and sick leave. includes anything the employee receives for his or her work. In addition, HRM professionals need to make sure the pay is comparable to what other people performing similar jobs are being paid. This involves setting up pay systems that take into consideration the number of years with the organization, years of experience, education, and similar aspects. Examples of employee compensation include the following: Pay
Health benefits
401 (k) (retirement plans)
Stock purchase plans
Vacation time
Sick leave
Bonuses
Tuition reimbursement
Since this is not an exhaustive list, compensation is discussed further in Chapter 6 "Compensation and Benefits". Retention
Retention
The process and strategies of keeping and motivating employees to stay with the organization.
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http://2012books.lardbucket.org/books/beginning-management-of-human-resources/s05-the-role-of-human-resources.html
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The Role of Human Resources
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Chapter 1
The Role of Human Resources
Chapter 1 The Role of Human Resources
Human Resource Management Day to Day
The Role of Human Resources
1.1 What Is Human Resources?
Learning Objectives
What Is HRM?
Human Resource Recall
The Role of HRM
Staffing
Development of Workplace Policies
Compensation and Benefits Administration
Retention
Training and Development
Dealing with Laws Affecting Employment
Worker Protection
Communication
Awareness of External Factors
Key Takeaways
Exercises
1.2 Skills Needed for HRM
Learning Objectives
Dilbert and the Evil HR Director
Human Resource Recall
People Skills in HR
Key Takeaways
Exercise
1.3 Today’s HRM Challenges
Learning Objective
Containing Costs
Technology
How Would You Handle This?
The Economy
The Changing and Diverse Workforce
Fortune 500 Focus
Human Resource Recall
Ethics
Key Takeaways
Exercises
1.4 Cases and Problems
Chapter Summary
Chapter Case
Team Activities
|
In addition, HRM professionals need to make sure the pay is comparable to what other people performing similar jobs are being paid. This involves setting up pay systems that take into consideration the number of years with the organization, years of experience, education, and similar aspects. Examples of employee compensation include the following: Pay
Health benefits
401 (k) (retirement plans)
Stock purchase plans
Vacation time
Sick leave
Bonuses
Tuition reimbursement
Since this is not an exhaustive list, compensation is discussed further in Chapter 6 "Compensation and Benefits". Retention
Retention
The process and strategies of keeping and motivating employees to stay with the organization. involves keeping and motivating employees to stay with the organization. Compensation is a major factor in employee retention, but there are other factors as well. Ninety percent of employees leave a company for the following reasons: Issues around the job they are performing
Challenges with their manager
Poor fit with organizational culture
Poor workplace environment
Despite this, 90 percent of managers think employees leave as a result of pay. Leigh Rivenbark, “The 7 Hidden Reasons Why Employees Leave,” HR Magazine, May 2005, accessed October 10, 2010, http://findarticles.com/p/articles/mi_m3495/is_5_50/ai_n13721406.
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