# Study of Compounds — Ammonia

## Intext Questions

#### Question 1

(a) State the type of bonding present in ammonia, show by a diagram.

(b) What is the formula of liquid ammonia? Account for the basic nature of this compound.

(a) Covalent bonding is present in ammonia as shown below — (b) The formula of liquid ammonia is NH4OH.

The aqueous solution of ammonia [NH4OH] is a weak base. It dissociates partially to give hydroxyl ions [OH1-].

The basic nature of NH4OH is due to the presence of hydroxyl ions [OH1-].

NH3 + H2O ⟶ NH4OH

NH4OH ⇌ NH4+ + OH-

#### Question 2

(a) Write a balanced chemical equation for the lab preparation of ammonia.

(b) How is ammonia dried and collected in the laboratory?

(c) Ammonia cannot be collected over water. Give reason.

(a) 2NH4Cl + Ca(OH)2 ⟶ CaCl2 + 2H2O + 2NH3 [g]

(b) In order to get dry ammonia, the gas is passed through a drying tower containing lumps of quicklime [CaO]. Ammonia gas is collected in inverted gas jars by the downward displacement of air.

(c) As ammonia gas is highly soluble in water, therefore, it is not collected over water.

#### Question 3

(a) Explain with a diagram the preparation of aqueous ammonia.

(b) Why drying agents such as P2O5 and CaCl2 are not used to dry NH3 ?

(a) The diagram below shows the preparation of aqueous ammonia: Procedure : Water is taken in a container and only a small portion of the mouth of the funnel is dipped in water.

As ammonia dissolves in water at a higher rate than it's production in the flask, the pressure in the funnel above water level decreases for a moment and water rushes into the funnel.

As a result, the rim of the funnel loses it's contact with water. Since, ammonia produced pushes the water down, the funnel comes in contact with water again. In this way, ammonia dissolves in water without back suction of water.

(b) Ammonia being basic in nature reacts chemically with P2O5 and CaCl2

6NH3 + P2O5 + 3H2O ⟶ 2(NH4)3PO4

4NH3 + CaCl2 ⟶ CaCl2.4NH3

Hence, P2O5 and CaCl2 are not used to dry NH3

#### Question 4

A substance 'A' was heated with slaked lime and a gas 'B' with a pungent smell was obtained. Name the substances A and B and give a balanced equation.

Substance A is Ammonium chloride (NH4Cl) and gas B is Ammonia

2NH4Cl + Ca(OH)2 ⟶ CaCl2 + 2H2O + 2NH3 [g]

#### Question 5

Ammonia is manufactured by Haber's process —

(a) Under what conditions do the reactants combine to form ammonia? Give a balanced equation for the reaction.

(b) In what ratio by volume, are the above gases used?

(c) State one possible source of each reactant used in Haber Process.

(d) State whether the formation of ammonia is promoted by the use of high pressure or low pressure?

(e) Mention two possible ways by which ammonia produced is removed from unchanged gases.

(f) What is the function of

(i) finely divided iron,

(ii) molybdenum

in the above process?

(g) What is the percentage formation of ammonia?

(h) How can this percentage formation be increased?

(a) Nitrogen reacts with hydrogen under specific conditions liberating ammonia

N2 + 3H2 ⇌ 2NH3 + Δ

Conditions :

Temperature : 450-500°C [Optimum temperature]

Pressure : 200 to 900 atmospheres [Optimum pressure]

Catalyst : Finely divided iron [Fe]

Promotor : Molybdenum [Mo]

[Catalyst - iron [III] oxide [Fe2O3] may also be used containing promoters about 1% K2O and 3% Al2O3]

(b) According to the above equation, nitrogen and hydrogen combines in 1:3 ratio by volume.

(c) Nitrogen is obtained by fractional distillation of liquid air. Hydrogen is obtained from the water gas (Bosch process) or from natural gas.

(d) The formation of ammonia is promoted by the use of high pressure as it favours the forward direction.

(e) Two possible ways by which ammonia produced is removed from unchanged gases are:

1. By Liquefaction — ammonia is liquefied easily as compared to nitrogen and hydrogen.
2. By Absorbing in water — because ammonia is highly soluble in water, as hydrogen and nitrogen are very slightly soluble.

(f) Function of finely divided iron and molybdenum are:

1. Finely divided iron increases the rate of reaction.
2. Molybdenum acts as a promoter to increase the efficiency of the catalyst.

(g) 15%

(h) The unchanged nitrogen and hydrogen are recirculated through the plant to get more ammonia, by this way we can achieve 98% of ammonia.

#### Question 6a

Give reason —

Ammonium compounds does not occur in minerals.

Due to the high solubility of Ammonium compounds in water it does not occur in minerals.

#### Question 6b

Give reason —

Ammonium nitrate is not used in the preparation of ammonia.

As ammonium nitrate is explosive in nature and may itself decompose forming nitrous oxide and water vapour, hence it is not used in the preparation of ammonia.

NH4NO3 $\xrightarrow{\Delta}$ N2O + 2H2O

#### Question 6c

Give reason —

Conc. H2SO4 is a good drying agent, yet it is not used to dry NH3.

As sulphuric acid reacts chemically with ammonia to form ammonium sulphate hence, it is not used as a drying agent for drying ammonia.

2NH3 + H2SO4 ⟶ (NH4)2SO4

#### Question 6d

Give reason —

In the lab. preparation of ammonia

1. calcium hydroxide is used in excess.
2. Flask is fitted in slanting position.

1. In the lab preparation of ammonia, ammonium chloride is used. Ammonium chloride is sublime, during the reaction, the heat will cause ammonium chloride to vapourise. To prevent this, calcium hydroxide is used in excess. It absorbs excess heat and prevents the loss of ammonium chloride as vapours.
2. The flask is fitted in slanting position so that the water formed in the reaction does not trickle back into the heated flask and thus break it.

#### Question 7

State the following conditions required in the Haber's process-

(a) Temperature

(b) Pressure

(c) Catalyst

Conditions :

(a) Temperature : 450-500°C [Optimum temperature]

(b) Pressure : 200 to 900 atmospheres [Optimum pressure]

(c) Catalyst : Finely divided iron [Fe]

#### Question 8

Choose the correct word or phrase from the brackets to complete the following sentences and write balanced equations for the same.

(a) Ammonium chloride is a soluble salt prepared by ............... [precipitation, neutralization].

(b) When ammonium chloride is heated, it undergoes ............... [thermal decomposition/dissociation].

(c) Heating ammonium chloride with sodium hydroxide produces ............... [ammonia, nitrogen].

(a) Ammonium chloride is a soluble salt prepared by neutralization.

NH3 (gas) + HCl (gas) ⟶ NH4Cl (solid)

(b) When ammonium chloride is heated, it undergoes thermal dissociation.

NH4Cl ⇌ NH3 + HCl

(c) Heating ammonium chloride with sodium hydroxide produces ammonia.

NH4Cl + NaOH ⟶ NaCl+ H2O + NH3

#### Question 9

An element has 2 electrons in it's N shell. It reacts with a non-metal of atomic number 7. The compound formed reacts with warm water and produces a basic gas. Identify the elements and write the balanced chemical reactions.

An element has 2 electrons in it's N shell, hence, it has

1. 2 (electrons in K shell) +
2. 8 (electrons in L shell) +
3. 8 (electrons in M shell) +
4. 2 (electrons in N shell) = 20 electrons total i.e. Calcium

Non metal (atomic number 7) is Nitrogen

Calcium and Nitrogen react to form calcium nitride.

3Ca + N2 ⟶ Ca3N2

Ca3N2 reacts with water to give calcium hydroxide and ammonia.

Ca3N2 + 6H2O ⟶ 3Ca(OH)2 + 2NH3 [g]

#### Question 10

The following reactions are carried out

A: Nitrogen + metal ⟶ compound X.

B: X + water ⟶ ammonia + another compound.

C: Ammonia + metal oxide ⟶ metal + water + N2

One metal that can be used for reaction A is magnesium.

(a) Write the formula of the compound X formed

(b) Write the correctly balanced equation for reaction B where X is the compound formed.

(c) What property of ammonia is demonstrated by reaction C ?

(a) When metal for A is magnesium, then, compound X is Mg3N2

N2 + 3Mg ⟶ Mg3N2

(b) Magnesium nitride

Mg3N2 + 6H2O ⟶ 3Mg(OH)2 + 2NH3 [g]

(c) Ammonia is a reducing agent and hence it reduces the less reactive metal oxide to the respective metal.

2NH3 + 3MgO ⟶ 3Mg + 3H2O + N2

#### Question 11

Correct the following:

(a) A reddish-brown precipitate is obtained when ammonium hydroxide is added to ferrous sulphate.

(b) Liquid ammonia is a solution of NH3.

(c) Finely divided platinum is used in Haber's Process.

(d) Conc. H2SO4 is a drying agent for NH3.

(e) Ammonium salts, on heating, decompose to give ammonia.

(a) A dirty green precipitate is obtained when ammonium hydroxide is added to ferrous sulphate.

(b) Aqueous ammonia is a solution of NH3 in water.

(c) Finely divided iron is used in Haber's Process.

(d) Quicklime, is a drying agent for NH3,

(e) Ammonium salts, on heating with caustic alkali, decompose to give ammonia.

#### Question 12

Choose the correct from the following:

Ammonia can be obtained by adding water to

A : Ammonium chloride.

B : Ammonium nitrite.

C : Magnesium nitride.

D : Magnesium nitrate

Magnesium nitride

Mg3N2 + 6H2O ⟶ 3Mg(OH)2 + 2NH3 [g]

## Exercise 9

#### Question 1

(a) Is ammonia more dense or less dense than air?

(b) What property of ammonia is demonstrated by the Fountain Experiment?

(c) Write the balanced equation for the reaction between ammonia and sulphuric acid.

(a) Ammonia is less dense than air because vapour density of ammonia is 8.5 and that of air is 14.4.

(b) Fountain Experiment demonstrates the high solubility of ammonia gas in water.

(c) 2NH3 + H2SO4 ⟶ (NH4)2SO4

#### Question 2

Pick the odd member from the list giving reasons:

(a) Ammonia, sulphur dioxide, hydrogen chloride, carbon dioxide.

(b) Copper oxide, aluminium oxide, sodium oxide, magnesium oxide.

(a) Ammonia is basic in nature and rest are acidic.

(b) Copper oxide is less reactive and can be reduced by C, CO or hydrogen whereas aluminium oxide, sodium oxide, magnesium oxide are reduced by electrolysis.

#### Question 3

Give reasons for the following —

(a) Liquid ammonia is used as a refrigerant in ice plants.

(b) Aqueous solution of ammonia is used for removing grease stains from woollen clothes.

(c) Aqueous solution of ammonia gives a pungent smell.

(d) Aqueous solution of ammonia conducts electricity.

(a) Liquid ammonia is a clear, colourless liquid under pressure. It evaporates rapidly and produces cooling effect. Moreover, Ammonia is environmentally compatible, has superior thermodynamic properties and its leaks are easily detectable due to its recognizable odour. All these reasons make liquid ammonia a good refrigerant.

(b) As aqueous solution of ammonia emulsifies or dissolves fats, grease etc., hence it is used for removing grease stains from woollen clothes.

(c) Pungent smell of aqueous solution of ammonia is due to the presence of ammonia, which has strong, pungent choking smell.

(d) In aqueous solution, the ammonia molecule combines with a hydrogen atom H+ by sharing the lone pair of electrons of nitrogen atom to form ammonium ion (NH4+). Thus, in water, ammonium hydroxide (NH4OH) dissociates into NH4+ (ammonium ion) and OH- (hydroxide ion) as follows:

NH4OH ⟶ NH4+ + OH-

Due to this ionisation, aqueous solution of ammonia (NH4OH) conducts electricity.

#### Question 4

A gas 'P' gives dense white fumes with chlorine. It's aqueous solution gives a blue colour with copper (II) hydroxide. Give the name and formula of the gas P.

Gas 'P' is Ammonia and its formula is NH3.

With chlorine, ammonia gas gives dense white fumes of NH4Cl.

8NH3 [excess] + 3Cl2 ⟶ 6NH4Cl + N2

Reaction of copper (II) hydroxide with aqueous solution of Ammonia (NH4OH) is given below:

Cu(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Cu(NH3)4]SO4 + 4H2O

#### Question 5

Ammonia solution in water gives a blue precipitate when it combines with a solution of copper salt. The blue precipitate further dissolves in excess of ammonia solution to give an azure blue solution. Explain with equation.

Ammonia solution in water gives a blue precipitate when it combines with a solution of copper salt, due to the formation of Cu(OH)2

CuSO4 + 2NH4OH ⟶ (NH4)2SO4 + Cu(OH)2

The pale blue precipitate of copper hydroxide dissolves in excess of ammonium hydroxide forming tetraamine copper [II] sulphate, an azure blue soluble complex salt.

Cu(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Cu(NH3)4]SO4 + 4H2O

#### Question 6

Give chemical equation(s) to prove that NH3 contains nitrogen and hydrogen?

Ammonia dissociates into nitrogen and hydrogen at high temperature or by electric sparks

2NH3 ⇌ N2 + 3H2

#### Question 7

Copy and complete the following equations.

(a) AlN + H2O ⟶

(b) 2NH3 + 3PbO ⟶

(c) NH3 + 3Cl2

(d) NH3 + CO2

(i) Which property of ammonia is illustrated by equation (c)?

(ii) What important fertiliser is prepared from equation (d)? State the conditions.

(a) AlN + 3H2O ⟶ Al(OH)3 + NH3

(b) 2NH3 + 3PbO ⟶ 3Pb + 3H2O + N2 [g]

(c) NH3 + 3Cl2 [excess] ⟶ 3HCl + NCl3

(d) 2NH3 + CO2 ⟶ NH2CONH2 + H2O

(i) Ammonia acts as a reducing agent as it loses hydrogen in equation (c).

(ii) Urea is prepared from equation (d). Ammonia reacts with carbon dioxide at 150°C and 150 atm, pressure to give urea.

#### Question 8

(a) What do you observe when ammonium hydroxide is added to the aqueous solution of :

(i) FeSO4

(ii) Iron (III) chloride.

(iv) Zinc nitrate

(b) Write balanced equation for Q.8(a).

(i) Dirty green ppt. of ferrous hydroxide is formed which is insoluble in excess of NH4OH.

(ii) Reddish brown ppt. of ferric hydroxide is formed which is insoluble in excess of NH4OH.

(iii) White ppt. of lead hydroxide is formed which is insoluble in excess of NH4OH.

(iv) White gelatinous ppt. of Zinc hydroxide is formed which is soluble in excess of NH4OH.

(b) The balanced chemical equations are given as :

(i) FeSO4 + 2NH4OH ⟶ (NH4)2SO4 + Fe(OH)2

(ii) FeCl3 + 3NH4OH ⟶ 3NH4Cl + Fe(OH)3

(iii) Pb(NO3)2 + 2NH4OH ⟶ 2NH4NO3 + Pb(OH)2

(iv) Zn(NO3)2 + 2NH4OH ⟶ 2NH4NO3 + Zn(OH)2

#### Question 9

Distinguish between the following (using ammonia solution) :

(a) Calcium chloride and zinc chloride.

(b) Ferric salt and ferrous salt

(c) Zinc nitrate and lead nitrate

(a) When we add ammonium hydroxide solution to both the given salt solutions, Zinc Chloride reacts to form a gelatinous white precipitate of Zinc Hydroxide (ZnOH), whereas, no such observations i.e no precipitate will form in case of Calcium Chloride solution because ammonium hydroxide is a weak base and it cannot react with calcium salts to precipitate the hydroxide of calcium.

ZnCl2 + 2NH4OH ⟶ Zn(OH)2 + 2NH4Cl

(b) On reaction with ammonium hydroxide, Iron [II] sulphate (ferrous salt) forms a dirty green ppt whereas iron [III] sulphate (ferric salt) forms a reddish brown ppt. Hence, the two can be distinguished easily.

FeSO4 + 2NH4OH ⟶ (NH4)2SO4 + Fe(OH)2

Fe2(SO4)3 + 6NH4OH ⟶ 3(NH4)2SO4 + 2Fe(OH)3

(c) When zinc nitrate is treated with ammonium hydroxide, white gelatinous ppt. of Zinc hydroxide is formed which is soluble in excess of NH4OH.

Zn(NO3)2 + 2NH4OH ⟶ 2NH4NO3 + Zn(OH)2

Whereas, when lead nitrate is treated with ammonium hydroxide, white ppt. of lead hydroxide is formed which is insoluble in excess of NH4OH

Pb(NO3)2 + 2NH4OH ⟶ 2NH4NO3 + Pb(OH)2

#### Question 10

Give balanced equations for the following conversions :

(a) Ammonia to nitrogen using an acidic gas.

(b) Ammonia to brown gas.

(c) Ammonia to nitrogen trichloride

(d) Ammonia solution to an amphoteric hydroxide

(e) A nitride of a trivalent metal to ammonia

(a) Ammonia to nitrogen using an acidic gas :

8NH3 [excess] + 3Cl2 ⟶ 6NH4Cl + N2

(b) Ammonia to brown gas:

$4\text{NH}_3 + 5\text{O}_2 \xrightarrow[800 \degree \text{C}]{\text{Pt.}} \text{4NO} + \text{6H}_\text{2}\text{O} + \Delta$

2NO + O2 ⟶ 2NO2 [brown gas]

(c) Ammonia to nitrogen trichloride

NH3 + 3Cl2 [excess] ⟶ 3HCl + NCl3

(d) Ammonia solution to an amphoteric hydroxide :

AlCl3 + 3NH4OH ⟶ 3NH4Cl + Al(OH)3

(e) A nitride of a trivalent metal to ammonia:

AlN + 3H2O ⟶ Al(OH)3 + NH3

2NH3 + 3PbO ⟶ 3Pb + 3H2O + N2 [g]

#### Question 11

Name:

(a) the gas which is prepared by Haber's process.

(b) two gases which give dense white fumes with ammonia.

(c) one salt of ammonia in each case which is used in:

(i) dry cell

(ii) explosives

(iii) medicine

(d) an acidic gas which reacts with a basic gas liberating a neutral gas

(e) a metallic chloride soluble in ammonium hydroxide

(f) the gas obtained when ammonia burns in an atmosphere of oxygen without any catalyst

(g) a nitride of a divalent metal which reacts with warm water liberating ammonia

(h) an amphoteric oxide reduced by the basic gas

(i) a white salt produced by an acidic gas and a basic gas

(a) Ammonia

(b) Hydrogen chloride and chlorine gas

(c) (i) dry cell — ammonium chloride

(ii) explosives — ammonium nitrate

(iii) medicine — ammonium carbonate

(d) Acidic gas — Cl2 ; Basic gas — Ammonia

Neutral gas — N2

2NH3 + 3Cl2 ⟶ N2 + 6HCl

(e) Silver chloride

(f) Nitrogen

(g) Magnesium nitride

(i) Ammonium chloride

#### Question 12

When ammonium hydroxide is added to solution B, a pale blue precipitate is formed. This pale blue precipitate dissolves in excess ammonium hydroxide giving an inky blue solution. What is the cation (positive ion) present in solution B? What is the probable colour of solution B.

Solution B is Copper Sulphate and cation present is (Cu2+). The colour of solution B is Blue.

Ammonium hydroxide gives a blue precipitate when it combines with a solution of copper salt, due to the formation of Cu(OH)2

CuSO4 + 2NH4OH ⟶ (NH4)2SO4 + Cu(OH)2

The pale blue precipitate of copper hydroxide dissolves in excess of ammonium hydroxide forming tetraamine copper [II] sulphate, an azure blue soluble complex salt.

Cu(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Cu(NH3)4]SO4 + 4H2O

#### Question 13

When an ammonium salt is warmed with sodium hydroxide solution, a gas is evolved. State three ways in which you could identify this gas.

When an ammonium salt is warmed with sodium hydroxide solution, ammonia gas is evolved.

NH4Cl + NaOH ⟶ NaCl + H2O + NH3

Three ways in which ammonia gas can be identified is:

1. It has a sharp characteristic odour.
2. It turns:
1. moist red litmus blue,
2. moist turmeric paper brown,
3. phenolphthalein solution pink.
3. It gives dense white fumes with conc. hydrochloric acid.
NH3 + HCl ⟶ NH4Cl

#### Question 14

A gas 'A' reacts with another gas 'B' in the presence of a catalyst to give a colourless gas 'C'. The gas 'C' when comes in contact with air produces a brown gas 'D'. The solution of 'A' in water turns red litmus blue. Explain the observations.

As the 'A' turns red litmus blue it is a base. Now the gas 'A' combines with 'B' in presence of Catalyst to give colourless gas Nitrogen monoxide. It reacts with oxygen to give brown gas which is Nitrogen dioxide. The gases are given as :

A = NH3
B = O2
C = NO
D = NO2

4NH3 + 5O2 $\xrightarrow[800 \degree \text{C}]{\text{Pt.}}$ 4NO↑ + 6H2O + Δ

2NO + O2 ⟶ 2NO2 [brown gas]

#### Question 15

(i) Name the common refrigerant. How does it deplete ozone layer?

(ii) What is the alternative of chlorofluorocarbon carbon?

(i) The main refrigerants used are Freon chlorofluorocarbons (CFC). They deplete ozone layer and contribute to global warming. The chlorofluorocarbons are decomposed by ultraviolet rays to highly reactive chlorine which is produced in the atomic form.

$\text{CF}_2\text{Cl}_2 \xrightarrow{\text{Ultraviolet}} \text{CF}_2\text{Cl} + \text{Cl} [\text{free radical}]$

The free radical [Cl] reacts with ozone and chlorine monoxide is formed.

Cl + O3 [ozone] ⟶ ClO + O2

This causes depletion of ozone. Chlorine monoxide further reacts with atomic oxygen and produces more free radicals.

ClO + O ⟶ Cl + O2

Again this free radical [Cl] destroys ozone, and the process continues thereby giving rise to ozone depletion.

(ii) Liquid ammonia

(iii) Advantages of ammonia as refrigerant:

1. Ammonia is environmentally compatible. It does not deplete ozone layer and does not contribute towards global warming.
2. It has superior thermodynamic qualities as result ammonia refrigeration systems use less electricity.
3. Ammonia has a recognizable odour and so leaks are not likely to escape. It being lighter than air goes up in the atmosphere not affecting the life too much on earth.

Disadvantages of ammonia as a refrigerant are as follows:

1. It is not compatible with copper, so it cannot be used in any system with copper pipes.
2. It is poisonous in high concentration.

#### Question 16

Name a compound prepared by ammonia and is used as :

(a) Explosive

(b) Fertilizers

(c) Medicine

(d) Laboratory reagent

(a) Ammonium nitrate

(b) Ammonium sulphate

(c) Ammonium carbonate

(d) Ammonia solution

#### Question 17

Write the equation for the action of heat on:

(a) Ammonium chloride

(b) Ammonium nitrate

State whether each reaction is an example of thermal decomposition or thermal dissociation.

(a) NH4Cl ⇌ NH3 + HCl

This reaction is an example of thermal dissociation.

(b) NH4NO3 ⇌ N2O + 2H2O

This reaction is an example of thermal dissociation.

#### Question 18

(a) Which feature of ammonia molecule leads to the formation of the ammonium ion when ammonia dissolves in water?

(b) Name the other ion formed when ammonia dissolves in water.

(c) Give one test that can be used to detect the presence of the ion produced in (b).

(a) Ammonia molecule has a lone pair of electrons on it's nitrogen atom. Due to this lone pair of electrons, in aqueous solutions it forms ammonium ion.

NH3 + H2O ⟶ NH4OH

NH4OH ⇌ NH4+ + OH-

(b) Hydroxyl ion [OH-].

(c) The red litmus paper turns blue due to the presence of hydroxyl ion in the solution.

#### Question 19

(a) Of the two gases, ammonia and hydrogen chloride, which is more dense? Name the method of collection of this gas.

(b) Give one example of a reaction between the above two gases which produces a solid compound.

(c) Write a balanced equation for a reaction in which ammonia is oxidized by:

(i) a metal oxide

(ii) a gas which is not oxygen.

(a) HCl gas is denser as it's vapour density = 18.25, and that of ammonia is 8.5. HCl gas is collected by the upward displacement of air.

(b) NH3 + HCl ⟶ NH4Cl

(c) (i) 2NH3 + 3CuO ⟶ 3Cu + 3H2O + N2

(ii) NH3 + 3Cl2 ⟶ 3HCl + NCl3

#### Question 20

Study the flow chart given and give balanced equations to represent the reactions A, B and C.

$\text{Mg}_3\text{N}_2 \xrightarrow{\text{A}} \text{NH}_3 \xtofrom[\text{C}]{\text{B}} \text{NH}_4\text{Cl}$

A : Mg3N2 + 6H2O ⟶ 3Mg(OH)2 + 2NH3 [g]

B:
$\underset{\text{[aq.]}}{\text{NH}_3} + \underset{\text{[vapour]}}{\text{HCl}} \longrightarrow \underset{\text{[dense white fumes]}}{\text{NH}_4\text{Cl}}$

C: 2NH4Cl + Ca(OH)2 ⟶ CaCl2 + 2H2O + 2NH3

#### Question 21

(a) Ammonia reacts with excess chorine to form ............... (nitrogen / nitrogen trichloride / ammonium chloride).

(b) Give a balanced equation: Ammonium hydroxide is added to ferrous sulphate solution.

(c) Write observations: Ammonia gas is passed over heated copper (II) oxide.

(a) Ammonia reacts with excess chlorine to form nitrogen trichloride

NH3 + 3Cl2 [excess] ⟶ 3HCl + NCl3

(b) FeSO4 + 2NH4OH ⟶ (NH4)2SO4 + Fe(OH)2

(c) Black copper [II] oxide is reduced to brown copper.

2NH3 + 3CuO ⟶ 3Cu + 3H2O + N2 [g]

#### Question 1a(2009)

Name the gas evolved in each case [formula is not acceptable]. The gas that burns in oxygen with a green flame.

Ammonia (NH3)

#### Question 1b(2009)

Write a fully balanced equation for — Magnesium nitride is treated with warm water.

Mg3N2 + 6H2O ⟶ 3Mg(OH)2 + 2NH3

#### Question 1c(2009)

Identity the substances 'Q' based on the information given — The white crystalline solid 'Q' is soluble in water. It liberates a pungent smelling gas when heated with sodium hydroxide solution.

Substances 'Q' are Ammonium salts like ammonium chloride, ammonium sulphate. They are white solids, soluble in water and liberate pungent smelling ammonia gas on heating with alkalis like NaOH.

#### Question 1a(2010)

Complete the blanks (i) to (v) in the passage given, using the following words. [Ammonium, reddish brown, hydroxyl, nitrogen dioxide, ammonia, dirty green, alkaline, acidic].

In the presence of a catalyst, nitrogen and hydrogen combine to give (i) .............. gas. When the same gas is passed through water, it forms a soln. which will be (ii).............. in nature, and will contain the ions (iii) .............. and (iv) ............... . A (v) .............. coloured ppt. of iron [II] hydroxide is formed when the above solution is added to iron [II] sulphate solution.

(i) Ammonia

(ii) Alkaline

(iii) Ammonium

(iv) Hydroxyl

(v) Dirty green

#### Question 1b(2010)

State your observation when — in the absence of catalyst, ammonia is burnt in an atmosphere of oxygen.

Green or greenish yellow flame is seen when ammonia gas is burnt in an atmosphere of oxygen. The reaction of combustion of Ammonia is:

4NH3 + 3O2 ⟶ 2N2 + 6H2O

#### Question 1c(2010)

Give the equation for the reaction — ammonium chloride is heated with sodium hydroxide.

NH4Cl + NaOH ⟶ NaCl + H2O + NH3

#### Question 1d(2010)

In the manufacture of ammonia:

(i) Name the process.

(ii) State the ratio of the reactants taken?

(iii) State the catalyst used.

(iv) Give the equation for the manufacture of the gas - ammonia.

(i) Haber's Process

(ii) Nitrogen (N2) and hydrogen (H2) in the ratio 1:3 by volume

(iii) Finely divided iron (Fe)

(iv) N2 + 3H2 ⇌ 2NH3 + Δ

#### Question 1e(2010)

Write a relevant equation, to show that ammonia can act as a reducing agent.

Ammonia gas is a strong reducing agent. Below equation shows reduction of Black Copper [II] oxide to brown Copper by Ammonia.

2NH3 + 3CuO ⟶ 3Cu + 3H2O + N2 [g]

#### Question 1f(2010)

Name two gases which can be used to study the fountain experiment. State the common property demonstrated by the fountain experiment ?

Hydrogen chloride gas (HCl) and Ammonia (NH3) are the two gases which can be used to study the fountain experiment.

The common property demonstrated by the fountain experiment is the solubility of gases in water.

#### Question 1a(2011)

State what is observed when – Ammonium hydroxide is first added in a small quantity and then in excess to a solution of copper sulphate.

Ammonium hydroxide if first added in small quantity and then in excess to a solution of copper sulphate, a pale blue ppt. of copper hydroxide is formed which dissolves in excess of ammonium hydroxide forming a soluble complex salt.

CuSO4 + 2NH4OH ⟶ (NH4)2SO4 + Cu(OH)2

Cu(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Cu(NH3)4]SO4 + 4H2O

#### Question 1b(2011)

The diagram below shows set up for the lab. preparation of a pungent alkaline gas. (i) Name the gas collected in the jar.

(ii) Give a balanced equation for the above preparation

(iii) State how the above gas is collected?

(iv) Name the drying agent used.

(v) State how you will find out that the jar is full of the pungent gas?

(i) Ammonia (NH3) gas is collected.

(ii) 2NH4Cl + Ca(OH)2 ⟶ CaCl2 + 2H2O + 2NH3

(iii) Downward displacement of air is the method used to collect the gas.

(iv) Quicklime (CaO) is the drying agent.

(v) A glass rod dipped in conc. HCl acid is brought near the mouth of the jar. If the jar is full-dense white fumes of ammonium chloride are formed.

#### Question 1c(2011)

Write a balanced chemical equation – Chlorine reacts with excess of ammonia.

8NH3 [excess] + 3Cl2 ⟶ 6NH4Cl + N2

#### Question 1d(2011)

State your observation – Water is added to the product formed, when Al is burnt in a jar of nitrogen gas.

When Al metal is burnt in a jar of nitrogen gas, its nitride i.e., AlN is formed. When warm water is added to AlN, it undergoes hydrolysis and is decomposed by warm water to give pungent smelling ammonia gas. The corresponding insoluble metal hydroxide (i.e., Al(OH)3) is precipitated out. The reactions are shown below:

2Al + N2 ⟶ 2AlN

AlN + 3H2O ⟶ Al(OH)3 + NH3 [g]

#### Question 1a(2012)

Name — The gas produced when excess ammonia reacts with chlorine.

Nitrogen

8NH3 [excess] + 3Cl2 ⟶ 6NH4Cl + N2

#### Question 1b(2012)

Rewrite the correct statement with the missing word/s — Magnesium nitride reacts with water to liberate ammonia.

Magnesium nitride reacts with warm water to liberate ammonia along with magnesium hydroxide.

#### Question 1c(2012)

Give balanced equation for the reaction : Ammonia and Oxygen in the presence of a catalyst.

Below is the equation for the catalytic oxidation of Ammonia:

$4\text{NH}_3 + 5\text{O}_2 \xrightarrow[800 \degree \text{C}]{\text{Pt.}} \text{4NO} + \text{6H}_\text{2}\text{O} + \Delta$

#### Question 1d(2012)

The following questions are based on the preparation of ammonia gas in the laboratory:

(i) Explain why ammonium nitrate is not used in the preparation of ammonia.

(ii) Name the compound normally used as a drying agent during the process.

(iii) How is ammonia gas collected? Explain why it is not collected over water.

(i) As ammonium nitrate is explosive in nature and may itself decompose forming nitrous oxide and water vapour, hence it is not used in the preparation of ammonia.

$\text{NH}_4\text{NO}_3 \xrightarrow\Delta \text{N}_2\text{O} + \text{2H}_2\text{O}$

(ii) Quick lime [CaO] is used as a drying agent during the process.

(iii) Downward displacement of air is the method used for the collection of the ammonia gas. As ammonia gas is highly soluble in water, therefore, it is not collected over water.

#### Question 1a(2013)

State one appropriate observation for : Excess of chlorine gas is reacted with ammonia gas.

Colourless ammonia gas reacts with greenish yellow excess chlorine giving a yellow explosive liquid (Nitrogen trichloride).

NH3 + 3Cl2 [excess] ⟶ 3HCl + NCl3

#### Question 1b(2013)

Nitrogen gas can be obtained by heating :

(a) Ammonium nitrate

(b) Ammonium nitrite

(c) Magnesium nitride

(d) Ammonium chloride

Ammonium nitrite

NH4NO2 $\xrightarrow\Delta$ 2H2O + N2

#### Question 1c(2013)

State two relevant observations for : ammonium hydroxide soln. is added to zinc nitrate soln. slowly and then in excess.

White gelatinous precipitate of zinc hydroxide is formed which dissolves in excess of NH4OH solution.

Zn(NO3)2 + 2NH4OH ⟶ 2NH4NO3 + Zn(OH)2

#### Question 1d(2013)

Give a balanced equation for : Reduction of hot Copper (II) oxide to copper using ammonia gas.

2NH3 + 3CuO ⟶ 3Cu + 3H2O + N2 [g]

#### Question 1e(2013)

Copy and complete the following table relating to important industrial process

Name of the processTemperatureCatalystEquation for the catalyzed reaction
Haber's process

Name of the processTemperatureCatalystEquation for the catalyzed reaction
Haber's process450 to 500°CFinely divided iron (Fe)N2 + 3H2 ⇌ 2NH3 + Δ

#### Question 1f(2013)

Identify : An alkaline gas which produces dense white fumes when reacted with HCl gas.

Ammonia gas.

NH3 + HCl ⟶ NH4Cl

#### Question 1a(2014)

Fill in the blank from the choices given in bracket : Ammonia gas is collected by .............. (upward displacement of air, downward displacement of water, downward displacement of air)

Ammonia gas is collected by downward displacement of air.

#### Question 1b(2014)

Write balanced equation for : Action of warm water on magnesium nitride.

Mg3N2 + 6H2O ⟶ 3Mg(OH)2 + 2NH3 [g]

#### Question 1c(2014)

Distinguish between the following pairs of compounds using the test given in bracket :

(i) Iron [II] sulphate and iron [III] sulphate [using ammonium hydroxide]

(ii) A lead salt and a zinc salt [using excess ammonium hydroxide]

(i) On reaction with ammonium hydroxide, Iron [II] sulphate forms a dirty green ppt whereas iron [III] sulphate forms a reddish brown ppt. Hence, the two can be distinguished easily.

FeSO4 + 2NH4OH ⟶ (NH4)2SO4 + Fe(OH)2

Fe2(SO4)3 + 6NH4OH ⟶ 3(NH4)2SO4 + 2Fe(OH)3

(ii) A lead salt gives a chalky white ppt. on reaction with ammonium hydroxide that is insoluble in excess of ammonium hydroxide.

Pb(NO3)2 + 2NH4OH ⟶ 2NH4NO3 + Pb(OH)2

On the other hand, zinc salt forms a white gelatinous ppt. which dissolves when excess of ammonium hydroxide is added. Hence, the two can be distinguished.

ZnSO4 + 2NH4OH ⟶ (NH4)2SO4 + Zn(OH)2

[Zn(OH)2] + (NH4)2SO4 + 2NH4OH ⟶ [Zn(NH3)4]SO4 + 4H2O

#### Question 1d(2014)

State your observation : Calcium hydroxide is heated with ammonium chloride crystals.

Pungent smelling gas (ammonia) is given out.

2NH4Cl + Ca(OH)2 ⟶ CaCl2 + 2H2O + 2NH3

#### Question 1e(2014)

Name the other ion formed when ammonia dissolves in water. Give one test that can be used to detect the presence of the ion produced.

Hydroxyl ion [OH-1] and ammonium ions [NH4+] are formed.

NH3 + H2O ⟶ NH4OH

NH4OH ⇌ NH4+ + OH-1

The alkaline NH4OH, due to the presence of hydroxyl ions [OH-] turns red litmus blue and phenolphthalein soln. pink

#### Question 1f(2014)

State the conditions required for : Catalytic oxidation of ammonia to nitric oxide.

Conditions for catalytic oxidation of ammonia to nitric oxide are :

1. Temperature : 800°C
2. Catalyst : Platinum (Pt)

$4\text{NH}_3 + 5\text{O}_2 \xrightarrow[800 \degree \text{C}]{\text{Pt.}} \text{4NO} + \text{6H}_\text{2}\text{O} + \Delta$

#### Question 1a(2015)

Give balanced chemical equations for —

(i) Lab. preparation of ammonia using an ammonium salt.

(ii) Reaction of ammonia with excess of chlorine.

(iii) Reaction of ammonia with sulphuric acid.

(i) 2NH4Cl + Ca(OH)2 ⟶ CaCl2 + 2H2O + 2NH3

(ii) NH3 + 3Cl2 [excess] ⟶ 3HCl + NCl3

(iii) 2NH3 + H2SO4 (dil.) ⟶ (NH4)2SO4

#### Question 1b(2015)

From the list of the gases — Ammonia, ethane, hydrogen chloride, hydrogen sulphide — Select the gas which is used as a reducing agent in reducing copper oxide to copper.

Ammonia

Reducing nature of ammonia:
2NH3 + 3CuO ⟶ 3Cu + 3H2O + N2 [g]

#### Question 1a(2016)

Name the gas evolved when the following mixtures are heated :

(i) Calcium hydroxide and Ammonium chloride.

(ii) Sodium nitrite and Ammonium chloride.

(i) Ammonia gas

2NH4Cl + Ca(OH)2 ⟶ CaCl2 + 2H2O + 2NH3

(ii) Nitrogen gas

NH4Cl + NaNO2 ⟶ NaCl + NH4NO2

NH4NO2 ⟶ 2H2O + N2

#### Question 1b(2016)

Write balanced equations :

(i) When excess of ammonia is treated with chlorine.

(ii) An equation to illustrate the reducing nature of ammonia.
{"ft_lang_label":"__label__en","ft_lang_prob":0.84403867,"math_prob":0.9158682,"size":33144,"snap":"2023-40-2023-50","text_gpt3_token_len":9672,"char_repetition_ratio":0.17854556,"word_repetition_ratio":0.16928446,"special_character_ratio":0.262853,"punctuation_ratio":0.1060013,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9789528,"pos_list":[0,1,2,3,4,5,6,7,8],"im_url_duplicate_count":[null,1,null,1,null,1,null,4,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-12-03T20:35:12Z\",\"WARC-Record-ID\":\"<urn:uuid:ddcaa598-e357-497b-9ffa-c22a10a77261>\",\"Content-Length\":\"477312\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:f00ef08d-f943-4d8c-bc20-fba9772af89c>\",\"WARC-Concurrent-To\":\"<urn:uuid:f6037762-58ef-46dc-9f8b-c08c2653878e>\",\"WARC-IP-Address\":\"35.74.145.57\",\"WARC-Target-URI\":\"https://www.knowledgeboat.com/learn/class-10-icse-concise-chemistry-selina/solutions/rGNzdj/ammonia-study\",\"WARC-Payload-Digest\":\"sha1:26VCQVGVPZRWOPYOSHMWRJC5UHFR2DS5\",\"WARC-Block-Digest\":\"sha1:YQZCJELRTGZJAAJLIQPXY5L64N4UV3K6\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-50/CC-MAIN-2023-50_segments_1700679100508.53_warc_CC-MAIN-20231203193127-20231203223127-00610.warc.gz\"}"}