Chapter
stringclasses 18
values | sentence_range
stringlengths 3
9
| Text
stringlengths 7
7.34k
|
|---|---|---|
1 | 4105-4108 | Complex compounds are those in which the metal ions bind a number
of anions or neutral molecules giving complex species with
characteristic properties A few examples are: [Fe(CN)6]
3–, [Fe(CN)6]
4–,
[Cu(NH3)4]
2+ and [PtCl4]
2– (The chemistry of complex compounds is
Rationalised 2023-24
104
Chemistry
dealt with in detail in Unit 5) The transition metals form a large
number of complex compounds |
1 | 4106-4109 | A few examples are: [Fe(CN)6]
3–, [Fe(CN)6]
4–,
[Cu(NH3)4]
2+ and [PtCl4]
2– (The chemistry of complex compounds is
Rationalised 2023-24
104
Chemistry
dealt with in detail in Unit 5) The transition metals form a large
number of complex compounds This is due to the comparatively
smaller sizes of the metal ions, their high ionic charges and the
availability of d orbitals for bond formation |
1 | 4107-4110 | (The chemistry of complex compounds is
Rationalised 2023-24
104
Chemistry
dealt with in detail in Unit 5) The transition metals form a large
number of complex compounds This is due to the comparatively
smaller sizes of the metal ions, their high ionic charges and the
availability of d orbitals for bond formation The transition metals and their compounds are known for their catalytic
activity |
1 | 4108-4111 | The transition metals form a large
number of complex compounds This is due to the comparatively
smaller sizes of the metal ions, their high ionic charges and the
availability of d orbitals for bond formation The transition metals and their compounds are known for their catalytic
activity This activity is ascribed to their ability to adopt multiple
oxidation states and to form complexes |
1 | 4109-4112 | This is due to the comparatively
smaller sizes of the metal ions, their high ionic charges and the
availability of d orbitals for bond formation The transition metals and their compounds are known for their catalytic
activity This activity is ascribed to their ability to adopt multiple
oxidation states and to form complexes Vanadium(V) oxide (in Contact
Process), finely divided iron (in Haber’s Process), and nickel (in Catalytic
Hydrogenation) are some of the examples |
1 | 4110-4113 | The transition metals and their compounds are known for their catalytic
activity This activity is ascribed to their ability to adopt multiple
oxidation states and to form complexes Vanadium(V) oxide (in Contact
Process), finely divided iron (in Haber’s Process), and nickel (in Catalytic
Hydrogenation) are some of the examples Catalysts at a solid surface
involve the formation of bonds between reactant molecules and atoms
of the surface of the catalyst (first row transition metals utilise 3d and
4s electrons for bonding) |
1 | 4111-4114 | This activity is ascribed to their ability to adopt multiple
oxidation states and to form complexes Vanadium(V) oxide (in Contact
Process), finely divided iron (in Haber’s Process), and nickel (in Catalytic
Hydrogenation) are some of the examples Catalysts at a solid surface
involve the formation of bonds between reactant molecules and atoms
of the surface of the catalyst (first row transition metals utilise 3d and
4s electrons for bonding) This has the effect of increasing the
concentration of the reactants at the catalyst surface and also weakening
of the bonds in the reacting molecules (the activation energy is lowering) |
1 | 4112-4115 | Vanadium(V) oxide (in Contact
Process), finely divided iron (in Haber’s Process), and nickel (in Catalytic
Hydrogenation) are some of the examples Catalysts at a solid surface
involve the formation of bonds between reactant molecules and atoms
of the surface of the catalyst (first row transition metals utilise 3d and
4s electrons for bonding) This has the effect of increasing the
concentration of the reactants at the catalyst surface and also weakening
of the bonds in the reacting molecules (the activation energy is lowering) Also because the transition metal ions can change their oxidation states,
they become more effective as catalysts |
1 | 4113-4116 | Catalysts at a solid surface
involve the formation of bonds between reactant molecules and atoms
of the surface of the catalyst (first row transition metals utilise 3d and
4s electrons for bonding) This has the effect of increasing the
concentration of the reactants at the catalyst surface and also weakening
of the bonds in the reacting molecules (the activation energy is lowering) Also because the transition metal ions can change their oxidation states,
they become more effective as catalysts For example, iron(III) catalyses
the reaction between iodide and persulphate ions |
1 | 4114-4117 | This has the effect of increasing the
concentration of the reactants at the catalyst surface and also weakening
of the bonds in the reacting molecules (the activation energy is lowering) Also because the transition metal ions can change their oxidation states,
they become more effective as catalysts For example, iron(III) catalyses
the reaction between iodide and persulphate ions 2 I
– + S2O8
2– ® I2 + 2 SO4
2–
An explanation of this catalytic action can be given as:
2 Fe
3+ + 2 I
– ® 2 Fe
2+ + I2
2 Fe
2+ + S2O8
2– ® 2 Fe
3+ + 2SO4
2–
Interstitial compounds are those which are formed when small atoms
like H, C or N are trapped inside the crystal lattices of metals |
1 | 4115-4118 | Also because the transition metal ions can change their oxidation states,
they become more effective as catalysts For example, iron(III) catalyses
the reaction between iodide and persulphate ions 2 I
– + S2O8
2– ® I2 + 2 SO4
2–
An explanation of this catalytic action can be given as:
2 Fe
3+ + 2 I
– ® 2 Fe
2+ + I2
2 Fe
2+ + S2O8
2– ® 2 Fe
3+ + 2SO4
2–
Interstitial compounds are those which are formed when small atoms
like H, C or N are trapped inside the crystal lattices of metals They are
usually non stoichiometric and are neither typically ionic nor covalent,
for example, TiC, Mn4N, Fe3H, VH0 |
1 | 4116-4119 | For example, iron(III) catalyses
the reaction between iodide and persulphate ions 2 I
– + S2O8
2– ® I2 + 2 SO4
2–
An explanation of this catalytic action can be given as:
2 Fe
3+ + 2 I
– ® 2 Fe
2+ + I2
2 Fe
2+ + S2O8
2– ® 2 Fe
3+ + 2SO4
2–
Interstitial compounds are those which are formed when small atoms
like H, C or N are trapped inside the crystal lattices of metals They are
usually non stoichiometric and are neither typically ionic nor covalent,
for example, TiC, Mn4N, Fe3H, VH0 56 and TiH1 |
1 | 4117-4120 | 2 I
– + S2O8
2– ® I2 + 2 SO4
2–
An explanation of this catalytic action can be given as:
2 Fe
3+ + 2 I
– ® 2 Fe
2+ + I2
2 Fe
2+ + S2O8
2– ® 2 Fe
3+ + 2SO4
2–
Interstitial compounds are those which are formed when small atoms
like H, C or N are trapped inside the crystal lattices of metals They are
usually non stoichiometric and are neither typically ionic nor covalent,
for example, TiC, Mn4N, Fe3H, VH0 56 and TiH1 7, etc |
1 | 4118-4121 | They are
usually non stoichiometric and are neither typically ionic nor covalent,
for example, TiC, Mn4N, Fe3H, VH0 56 and TiH1 7, etc The formulas
quoted do not, of course, correspond to any normal oxidation state of
the metal |
1 | 4119-4122 | 56 and TiH1 7, etc The formulas
quoted do not, of course, correspond to any normal oxidation state of
the metal Because of the nature of their composition, these compounds
are referred to as interstitial compounds |
1 | 4120-4123 | 7, etc The formulas
quoted do not, of course, correspond to any normal oxidation state of
the metal Because of the nature of their composition, these compounds
are referred to as interstitial compounds The principal physical and
chemical characteristics of these compounds are as follows:
(i) They have high melting points, higher than those of pure metals |
1 | 4121-4124 | The formulas
quoted do not, of course, correspond to any normal oxidation state of
the metal Because of the nature of their composition, these compounds
are referred to as interstitial compounds The principal physical and
chemical characteristics of these compounds are as follows:
(i) They have high melting points, higher than those of pure metals (ii) They are very hard, some borides approach diamond in hardness |
1 | 4122-4125 | Because of the nature of their composition, these compounds
are referred to as interstitial compounds The principal physical and
chemical characteristics of these compounds are as follows:
(i) They have high melting points, higher than those of pure metals (ii) They are very hard, some borides approach diamond in hardness (iii) They retain metallic conductivity |
1 | 4123-4126 | The principal physical and
chemical characteristics of these compounds are as follows:
(i) They have high melting points, higher than those of pure metals (ii) They are very hard, some borides approach diamond in hardness (iii) They retain metallic conductivity (iv) They are chemically inert |
1 | 4124-4127 | (ii) They are very hard, some borides approach diamond in hardness (iii) They retain metallic conductivity (iv) They are chemically inert An alloy is a blend of metals prepared by mixing the components |
1 | 4125-4128 | (iii) They retain metallic conductivity (iv) They are chemically inert An alloy is a blend of metals prepared by mixing the components Alloys may be homogeneous solid solutions in which the atoms of one
metal are distributed randomly among the atoms of the other |
1 | 4126-4129 | (iv) They are chemically inert An alloy is a blend of metals prepared by mixing the components Alloys may be homogeneous solid solutions in which the atoms of one
metal are distributed randomly among the atoms of the other Such
alloys are formed by atoms with metallic radii that are within about 15
percent of each other |
1 | 4127-4130 | An alloy is a blend of metals prepared by mixing the components Alloys may be homogeneous solid solutions in which the atoms of one
metal are distributed randomly among the atoms of the other Such
alloys are formed by atoms with metallic radii that are within about 15
percent of each other Because of similar radii and other characteristics
of transition metals, alloys are readily formed by these metals |
1 | 4128-4131 | Alloys may be homogeneous solid solutions in which the atoms of one
metal are distributed randomly among the atoms of the other Such
alloys are formed by atoms with metallic radii that are within about 15
percent of each other Because of similar radii and other characteristics
of transition metals, alloys are readily formed by these metals The
alloys so formed are hard and have often high melting points |
1 | 4129-4132 | Such
alloys are formed by atoms with metallic radii that are within about 15
percent of each other Because of similar radii and other characteristics
of transition metals, alloys are readily formed by these metals The
alloys so formed are hard and have often high melting points The best
known are ferrous alloys: chromium, vanadium, tungsten, molybdenum
and manganese are used for the production of a variety of steels and
stainless steel |
1 | 4130-4133 | Because of similar radii and other characteristics
of transition metals, alloys are readily formed by these metals The
alloys so formed are hard and have often high melting points The best
known are ferrous alloys: chromium, vanadium, tungsten, molybdenum
and manganese are used for the production of a variety of steels and
stainless steel Alloys of transition metals with non transition metals
such as brass (copper-zinc) and bronze (copper-tin), are also of
considerable industrial importance |
1 | 4131-4134 | The
alloys so formed are hard and have often high melting points The best
known are ferrous alloys: chromium, vanadium, tungsten, molybdenum
and manganese are used for the production of a variety of steels and
stainless steel Alloys of transition metals with non transition metals
such as brass (copper-zinc) and bronze (copper-tin), are also of
considerable industrial importance 4 |
1 | 4132-4135 | The best
known are ferrous alloys: chromium, vanadium, tungsten, molybdenum
and manganese are used for the production of a variety of steels and
stainless steel Alloys of transition metals with non transition metals
such as brass (copper-zinc) and bronze (copper-tin), are also of
considerable industrial importance 4 3 |
1 | 4133-4136 | Alloys of transition metals with non transition metals
such as brass (copper-zinc) and bronze (copper-tin), are also of
considerable industrial importance 4 3 12 Catalytic
Properties
4 |
1 | 4134-4137 | 4 3 12 Catalytic
Properties
4 3 |
1 | 4135-4138 | 3 12 Catalytic
Properties
4 3 13 Formation
of
Interstitial
Compounds
4 |
1 | 4136-4139 | 12 Catalytic
Properties
4 3 13 Formation
of
Interstitial
Compounds
4 3 |
1 | 4137-4140 | 3 13 Formation
of
Interstitial
Compounds
4 3 14 Alloy
Formation
Rationalised 2023-24
105
The d- and f- Block Elements
Intext Question
Intext Question
Intext Question
Intext Question
Intext Question
4 |
1 | 4138-4141 | 13 Formation
of
Interstitial
Compounds
4 3 14 Alloy
Formation
Rationalised 2023-24
105
The d- and f- Block Elements
Intext Question
Intext Question
Intext Question
Intext Question
Intext Question
4 9 Explain why Cu
+ ion is not stable in aqueous solutions |
1 | 4139-4142 | 3 14 Alloy
Formation
Rationalised 2023-24
105
The d- and f- Block Elements
Intext Question
Intext Question
Intext Question
Intext Question
Intext Question
4 9 Explain why Cu
+ ion is not stable in aqueous solutions 4 |
1 | 4140-4143 | 14 Alloy
Formation
Rationalised 2023-24
105
The d- and f- Block Elements
Intext Question
Intext Question
Intext Question
Intext Question
Intext Question
4 9 Explain why Cu
+ ion is not stable in aqueous solutions 4 4
4 |
1 | 4141-4144 | 9 Explain why Cu
+ ion is not stable in aqueous solutions 4 4
4 4
4 |
1 | 4142-4145 | 4 4
4 4
4 4
4 |
1 | 4143-4146 | 4
4 4
4 4
4 4
4 |
1 | 4144-4147 | 4
4 4
4 4
4 4 Some
Some
Some
Some
Some
Important
Important
Important
Important
Important
Compounds of
Compounds of
Compounds of
Compounds of
Compounds of
Transition
Transition
Transition
Transition
Transition
Elements
Elements
Elements
Elements
Elements
What is meant by ‘disproportionation’ of an oxidation state |
1 | 4145-4148 | 4
4 4
4 4 Some
Some
Some
Some
Some
Important
Important
Important
Important
Important
Compounds of
Compounds of
Compounds of
Compounds of
Compounds of
Transition
Transition
Transition
Transition
Transition
Elements
Elements
Elements
Elements
Elements
What is meant by ‘disproportionation’ of an oxidation state Give an
example |
1 | 4146-4149 | 4
4 4 Some
Some
Some
Some
Some
Important
Important
Important
Important
Important
Compounds of
Compounds of
Compounds of
Compounds of
Compounds of
Transition
Transition
Transition
Transition
Transition
Elements
Elements
Elements
Elements
Elements
What is meant by ‘disproportionation’ of an oxidation state Give an
example When a particular oxidation state becomes less stable relative to other
oxidation states, one lower, one higher, it is said to undergo disproportionation |
1 | 4147-4150 | 4 Some
Some
Some
Some
Some
Important
Important
Important
Important
Important
Compounds of
Compounds of
Compounds of
Compounds of
Compounds of
Transition
Transition
Transition
Transition
Transition
Elements
Elements
Elements
Elements
Elements
What is meant by ‘disproportionation’ of an oxidation state Give an
example When a particular oxidation state becomes less stable relative to other
oxidation states, one lower, one higher, it is said to undergo disproportionation For example, manganese (VI) becomes unstable relative to manganese(VII) and
manganese (IV) in acidic solution |
1 | 4148-4151 | Give an
example When a particular oxidation state becomes less stable relative to other
oxidation states, one lower, one higher, it is said to undergo disproportionation For example, manganese (VI) becomes unstable relative to manganese(VII) and
manganese (IV) in acidic solution 3 Mn
VIO4
2– + 4 H
+ ® 2 Mn
VIIO
–
4 + Mn
IVO2 + 2H2O
Example 4 |
1 | 4149-4152 | When a particular oxidation state becomes less stable relative to other
oxidation states, one lower, one higher, it is said to undergo disproportionation For example, manganese (VI) becomes unstable relative to manganese(VII) and
manganese (IV) in acidic solution 3 Mn
VIO4
2– + 4 H
+ ® 2 Mn
VIIO
–
4 + Mn
IVO2 + 2H2O
Example 4 9
Example 4 |
1 | 4150-4153 | For example, manganese (VI) becomes unstable relative to manganese(VII) and
manganese (IV) in acidic solution 3 Mn
VIO4
2– + 4 H
+ ® 2 Mn
VIIO
–
4 + Mn
IVO2 + 2H2O
Example 4 9
Example 4 9
Example 4 |
1 | 4151-4154 | 3 Mn
VIO4
2– + 4 H
+ ® 2 Mn
VIIO
–
4 + Mn
IVO2 + 2H2O
Example 4 9
Example 4 9
Example 4 9
Example 4 |
1 | 4152-4155 | 9
Example 4 9
Example 4 9
Example 4 9
Example 4 |
1 | 4153-4156 | 9
Example 4 9
Example 4 9
Example 4 9
Solution
Solution
Solution
Solution
Solution
4 |
1 | 4154-4157 | 9
Example 4 9
Example 4 9
Solution
Solution
Solution
Solution
Solution
4 4 |
1 | 4155-4158 | 9
Example 4 9
Solution
Solution
Solution
Solution
Solution
4 4 1 Oxides and Oxoanions of Metals
These oxides are generally formed by the reaction of metals with
oxygen at high temperatures |
1 | 4156-4159 | 9
Solution
Solution
Solution
Solution
Solution
4 4 1 Oxides and Oxoanions of Metals
These oxides are generally formed by the reaction of metals with
oxygen at high temperatures All the metals except scandium form
MO oxides which are ionic |
1 | 4157-4160 | 4 1 Oxides and Oxoanions of Metals
These oxides are generally formed by the reaction of metals with
oxygen at high temperatures All the metals except scandium form
MO oxides which are ionic The highest oxidation number in the
oxides, coincides with the group number and is attained in Sc2O3 to
Mn2O7 |
1 | 4158-4161 | 1 Oxides and Oxoanions of Metals
These oxides are generally formed by the reaction of metals with
oxygen at high temperatures All the metals except scandium form
MO oxides which are ionic The highest oxidation number in the
oxides, coincides with the group number and is attained in Sc2O3 to
Mn2O7 Beyond group 7, no higher oxides of iron above Fe2O3 are
known |
1 | 4159-4162 | All the metals except scandium form
MO oxides which are ionic The highest oxidation number in the
oxides, coincides with the group number and is attained in Sc2O3 to
Mn2O7 Beyond group 7, no higher oxides of iron above Fe2O3 are
known Besides the oxides, the oxocations stabilise V
V as VO2
+, V
IV as
VO
2+ and Ti
IV as TiO
2+ |
1 | 4160-4163 | The highest oxidation number in the
oxides, coincides with the group number and is attained in Sc2O3 to
Mn2O7 Beyond group 7, no higher oxides of iron above Fe2O3 are
known Besides the oxides, the oxocations stabilise V
V as VO2
+, V
IV as
VO
2+ and Ti
IV as TiO
2+ As the oxidation number of a metal increases, ionic character
decreases |
1 | 4161-4164 | Beyond group 7, no higher oxides of iron above Fe2O3 are
known Besides the oxides, the oxocations stabilise V
V as VO2
+, V
IV as
VO
2+ and Ti
IV as TiO
2+ As the oxidation number of a metal increases, ionic character
decreases In the case of Mn, Mn2O7 is a covalent green oil |
1 | 4162-4165 | Besides the oxides, the oxocations stabilise V
V as VO2
+, V
IV as
VO
2+ and Ti
IV as TiO
2+ As the oxidation number of a metal increases, ionic character
decreases In the case of Mn, Mn2O7 is a covalent green oil Even CrO3
and V2O5 have low melting points |
1 | 4163-4166 | As the oxidation number of a metal increases, ionic character
decreases In the case of Mn, Mn2O7 is a covalent green oil Even CrO3
and V2O5 have low melting points In these higher oxides, the acidic
character is predominant |
1 | 4164-4167 | In the case of Mn, Mn2O7 is a covalent green oil Even CrO3
and V2O5 have low melting points In these higher oxides, the acidic
character is predominant Thus, Mn2O7 gives HMnO4 and CrO3 gives H2CrO4 and H2Cr2O7 |
1 | 4165-4168 | Even CrO3
and V2O5 have low melting points In these higher oxides, the acidic
character is predominant Thus, Mn2O7 gives HMnO4 and CrO3 gives H2CrO4 and H2Cr2O7 V2O5 is, however, amphoteric though mainly acidic and it gives VO4
3– as
well as VO2
+ salts |
1 | 4166-4169 | In these higher oxides, the acidic
character is predominant Thus, Mn2O7 gives HMnO4 and CrO3 gives H2CrO4 and H2Cr2O7 V2O5 is, however, amphoteric though mainly acidic and it gives VO4
3– as
well as VO2
+ salts In vanadium there is gradual change from the basic
V2O3 to less basic V2O4 and to amphoteric V2O5 |
1 | 4167-4170 | Thus, Mn2O7 gives HMnO4 and CrO3 gives H2CrO4 and H2Cr2O7 V2O5 is, however, amphoteric though mainly acidic and it gives VO4
3– as
well as VO2
+ salts In vanadium there is gradual change from the basic
V2O3 to less basic V2O4 and to amphoteric V2O5 V2O4 dissolves in acids
to give VO
2+ salts |
1 | 4168-4171 | V2O5 is, however, amphoteric though mainly acidic and it gives VO4
3– as
well as VO2
+ salts In vanadium there is gradual change from the basic
V2O3 to less basic V2O4 and to amphoteric V2O5 V2O4 dissolves in acids
to give VO
2+ salts Similarly, V2O5 reacts with alkalies as well as acids
to give
43
VO and
4
VO respectively |
1 | 4169-4172 | In vanadium there is gradual change from the basic
V2O3 to less basic V2O4 and to amphoteric V2O5 V2O4 dissolves in acids
to give VO
2+ salts Similarly, V2O5 reacts with alkalies as well as acids
to give
43
VO and
4
VO respectively The well characterised CrO is basic
but Cr2O3 is amphoteric |
1 | 4170-4173 | V2O4 dissolves in acids
to give VO
2+ salts Similarly, V2O5 reacts with alkalies as well as acids
to give
43
VO and
4
VO respectively The well characterised CrO is basic
but Cr2O3 is amphoteric Potassium dichromate K2Cr2O7
Potassium dichromate is a very important chemical used in leather
industry and as an oxidant for preparation of many azo compounds |
1 | 4171-4174 | Similarly, V2O5 reacts with alkalies as well as acids
to give
43
VO and
4
VO respectively The well characterised CrO is basic
but Cr2O3 is amphoteric Potassium dichromate K2Cr2O7
Potassium dichromate is a very important chemical used in leather
industry and as an oxidant for preparation of many azo compounds Dichromates are generally prepared from chromate, which in turn are
obtained by the fusion of chromite ore (FeCr2O4) with sodium or
potassium carbonate in free access of air |
1 | 4172-4175 | The well characterised CrO is basic
but Cr2O3 is amphoteric Potassium dichromate K2Cr2O7
Potassium dichromate is a very important chemical used in leather
industry and as an oxidant for preparation of many azo compounds Dichromates are generally prepared from chromate, which in turn are
obtained by the fusion of chromite ore (FeCr2O4) with sodium or
potassium carbonate in free access of air The reaction with sodium
carbonate occurs as follows:
4 FeCr2O4 + 8 Na2CO3 + 7 O2 ® 8 Na2CrO4 + 2 Fe2O3 + 8 CO2
The yellow solution of sodium chromate is filtered and acidified
with sulphuric acid to give a solution from which orange sodium
dichromate, Na2Cr2O7 |
1 | 4173-4176 | Potassium dichromate K2Cr2O7
Potassium dichromate is a very important chemical used in leather
industry and as an oxidant for preparation of many azo compounds Dichromates are generally prepared from chromate, which in turn are
obtained by the fusion of chromite ore (FeCr2O4) with sodium or
potassium carbonate in free access of air The reaction with sodium
carbonate occurs as follows:
4 FeCr2O4 + 8 Na2CO3 + 7 O2 ® 8 Na2CrO4 + 2 Fe2O3 + 8 CO2
The yellow solution of sodium chromate is filtered and acidified
with sulphuric acid to give a solution from which orange sodium
dichromate, Na2Cr2O7 2H2O can be crystallised |
1 | 4174-4177 | Dichromates are generally prepared from chromate, which in turn are
obtained by the fusion of chromite ore (FeCr2O4) with sodium or
potassium carbonate in free access of air The reaction with sodium
carbonate occurs as follows:
4 FeCr2O4 + 8 Na2CO3 + 7 O2 ® 8 Na2CrO4 + 2 Fe2O3 + 8 CO2
The yellow solution of sodium chromate is filtered and acidified
with sulphuric acid to give a solution from which orange sodium
dichromate, Na2Cr2O7 2H2O can be crystallised 2Na2CrO4 + 2 H
+ ® Na2Cr2O7 + 2 Na
+ + H2O
Rationalised 2023-24
106
Chemistry
Sodium dichromate is more soluble than potassium dichromate |
1 | 4175-4178 | The reaction with sodium
carbonate occurs as follows:
4 FeCr2O4 + 8 Na2CO3 + 7 O2 ® 8 Na2CrO4 + 2 Fe2O3 + 8 CO2
The yellow solution of sodium chromate is filtered and acidified
with sulphuric acid to give a solution from which orange sodium
dichromate, Na2Cr2O7 2H2O can be crystallised 2Na2CrO4 + 2 H
+ ® Na2Cr2O7 + 2 Na
+ + H2O
Rationalised 2023-24
106
Chemistry
Sodium dichromate is more soluble than potassium dichromate The latter is therefore, prepared by treating the solution of sodium
dichromate with potassium chloride |
1 | 4176-4179 | 2H2O can be crystallised 2Na2CrO4 + 2 H
+ ® Na2Cr2O7 + 2 Na
+ + H2O
Rationalised 2023-24
106
Chemistry
Sodium dichromate is more soluble than potassium dichromate The latter is therefore, prepared by treating the solution of sodium
dichromate with potassium chloride Na2Cr2O7 + 2 KCl ® K2Cr2O7 + 2 NaCl
Orange crystals of potassium dichromate crystallise out |
1 | 4177-4180 | 2Na2CrO4 + 2 H
+ ® Na2Cr2O7 + 2 Na
+ + H2O
Rationalised 2023-24
106
Chemistry
Sodium dichromate is more soluble than potassium dichromate The latter is therefore, prepared by treating the solution of sodium
dichromate with potassium chloride Na2Cr2O7 + 2 KCl ® K2Cr2O7 + 2 NaCl
Orange crystals of potassium dichromate crystallise out The
chromates and dichromates are interconvertible in aqueous solution
depending upon pH of the solution |
1 | 4178-4181 | The latter is therefore, prepared by treating the solution of sodium
dichromate with potassium chloride Na2Cr2O7 + 2 KCl ® K2Cr2O7 + 2 NaCl
Orange crystals of potassium dichromate crystallise out The
chromates and dichromates are interconvertible in aqueous solution
depending upon pH of the solution The oxidation state of chromium
in chromate and dichromate is the same |
1 | 4179-4182 | Na2Cr2O7 + 2 KCl ® K2Cr2O7 + 2 NaCl
Orange crystals of potassium dichromate crystallise out The
chromates and dichromates are interconvertible in aqueous solution
depending upon pH of the solution The oxidation state of chromium
in chromate and dichromate is the same 2 CrO4
2– + 2H
+ ® Cr2O7
2– + H2O
Cr2O7
2– + 2 OH
- ® 2 CrO4
2– + H2O
The
structures
of
chromate ion, CrO4
2– and
the dichromate ion, Cr2O7
2–
are shown below |
1 | 4180-4183 | The
chromates and dichromates are interconvertible in aqueous solution
depending upon pH of the solution The oxidation state of chromium
in chromate and dichromate is the same 2 CrO4
2– + 2H
+ ® Cr2O7
2– + H2O
Cr2O7
2– + 2 OH
- ® 2 CrO4
2– + H2O
The
structures
of
chromate ion, CrO4
2– and
the dichromate ion, Cr2O7
2–
are shown below The
chromate ion is tetrahedral
whereas the dichromate ion
consists of two tetrahedra
sharing one corner with
Cr–O–Cr bond angle of 126° |
1 | 4181-4184 | The oxidation state of chromium
in chromate and dichromate is the same 2 CrO4
2– + 2H
+ ® Cr2O7
2– + H2O
Cr2O7
2– + 2 OH
- ® 2 CrO4
2– + H2O
The
structures
of
chromate ion, CrO4
2– and
the dichromate ion, Cr2O7
2–
are shown below The
chromate ion is tetrahedral
whereas the dichromate ion
consists of two tetrahedra
sharing one corner with
Cr–O–Cr bond angle of 126° Sodium and potassium dichromates are strong oxidising agents;
the sodium salt has a greater solubility in water and is extensively
used as an oxidising agent in organic chemistry |
1 | 4182-4185 | 2 CrO4
2– + 2H
+ ® Cr2O7
2– + H2O
Cr2O7
2– + 2 OH
- ® 2 CrO4
2– + H2O
The
structures
of
chromate ion, CrO4
2– and
the dichromate ion, Cr2O7
2–
are shown below The
chromate ion is tetrahedral
whereas the dichromate ion
consists of two tetrahedra
sharing one corner with
Cr–O–Cr bond angle of 126° Sodium and potassium dichromates are strong oxidising agents;
the sodium salt has a greater solubility in water and is extensively
used as an oxidising agent in organic chemistry Potassium dichromate
is used as a primary standard in volumetric analysis |
1 | 4183-4186 | The
chromate ion is tetrahedral
whereas the dichromate ion
consists of two tetrahedra
sharing one corner with
Cr–O–Cr bond angle of 126° Sodium and potassium dichromates are strong oxidising agents;
the sodium salt has a greater solubility in water and is extensively
used as an oxidising agent in organic chemistry Potassium dichromate
is used as a primary standard in volumetric analysis In acidic solution,
its oxidising action can be represented as follows:
Cr2O7
2– + 14H
+ + 6e
– ® 2Cr
3+ + 7H2O (E
o = 1 |
1 | 4184-4187 | Sodium and potassium dichromates are strong oxidising agents;
the sodium salt has a greater solubility in water and is extensively
used as an oxidising agent in organic chemistry Potassium dichromate
is used as a primary standard in volumetric analysis In acidic solution,
its oxidising action can be represented as follows:
Cr2O7
2– + 14H
+ + 6e
– ® 2Cr
3+ + 7H2O (E
o = 1 33V)
Thus, acidified potassium dichromate will oxidise iodides to iodine,
sulphides to sulphur, tin(II) to tin(IV) and iron(II) salts to iron(III) |
1 | 4185-4188 | Potassium dichromate
is used as a primary standard in volumetric analysis In acidic solution,
its oxidising action can be represented as follows:
Cr2O7
2– + 14H
+ + 6e
– ® 2Cr
3+ + 7H2O (E
o = 1 33V)
Thus, acidified potassium dichromate will oxidise iodides to iodine,
sulphides to sulphur, tin(II) to tin(IV) and iron(II) salts to iron(III) The
half-reactions are noted below:
6 I
– ® 3I2 + 6 e
– ;
3 Sn
2+ ® 3Sn
4+ + 6 e
–
3 H2S ® 6H
+ + 3S + 6e
– ;
6 Fe
2+ ® 6Fe
3+ + 6 e
–
The full ionic equation may be obtained by adding the half-reaction for
potassium dichromate to the half-reaction for the reducing agent, for e |
1 | 4186-4189 | In acidic solution,
its oxidising action can be represented as follows:
Cr2O7
2– + 14H
+ + 6e
– ® 2Cr
3+ + 7H2O (E
o = 1 33V)
Thus, acidified potassium dichromate will oxidise iodides to iodine,
sulphides to sulphur, tin(II) to tin(IV) and iron(II) salts to iron(III) The
half-reactions are noted below:
6 I
– ® 3I2 + 6 e
– ;
3 Sn
2+ ® 3Sn
4+ + 6 e
–
3 H2S ® 6H
+ + 3S + 6e
– ;
6 Fe
2+ ® 6Fe
3+ + 6 e
–
The full ionic equation may be obtained by adding the half-reaction for
potassium dichromate to the half-reaction for the reducing agent, for e g |
1 | 4187-4190 | 33V)
Thus, acidified potassium dichromate will oxidise iodides to iodine,
sulphides to sulphur, tin(II) to tin(IV) and iron(II) salts to iron(III) The
half-reactions are noted below:
6 I
– ® 3I2 + 6 e
– ;
3 Sn
2+ ® 3Sn
4+ + 6 e
–
3 H2S ® 6H
+ + 3S + 6e
– ;
6 Fe
2+ ® 6Fe
3+ + 6 e
–
The full ionic equation may be obtained by adding the half-reaction for
potassium dichromate to the half-reaction for the reducing agent, for e g ,
Cr2O7
2– + 14 H
+ + 6 Fe
2+ ® 2 Cr
3+ + 6 Fe
3+ + 7 H2O
Potassium permanganate KMnO4
Potassium permanganate is prepared by fusion of MnO2 with an alkali
metal hydroxide and an oxidising agent like KNO3 |
1 | 4188-4191 | The
half-reactions are noted below:
6 I
– ® 3I2 + 6 e
– ;
3 Sn
2+ ® 3Sn
4+ + 6 e
–
3 H2S ® 6H
+ + 3S + 6e
– ;
6 Fe
2+ ® 6Fe
3+ + 6 e
–
The full ionic equation may be obtained by adding the half-reaction for
potassium dichromate to the half-reaction for the reducing agent, for e g ,
Cr2O7
2– + 14 H
+ + 6 Fe
2+ ® 2 Cr
3+ + 6 Fe
3+ + 7 H2O
Potassium permanganate KMnO4
Potassium permanganate is prepared by fusion of MnO2 with an alkali
metal hydroxide and an oxidising agent like KNO3 This produces the
dark green K2MnO4 which disproportionates in a neutral or acidic
solution to give permanganate |
1 | 4189-4192 | g ,
Cr2O7
2– + 14 H
+ + 6 Fe
2+ ® 2 Cr
3+ + 6 Fe
3+ + 7 H2O
Potassium permanganate KMnO4
Potassium permanganate is prepared by fusion of MnO2 with an alkali
metal hydroxide and an oxidising agent like KNO3 This produces the
dark green K2MnO4 which disproportionates in a neutral or acidic
solution to give permanganate 2MnO2 + 4KOH + O2 ® 2K2MnO4 + 2H2O
3MnO4
2– + 4H+ ® 2MnO4
– + MnO2 + 2H2O
Commercially it is prepared by the alkaline oxidative fusion of MnO2
followed by the electrolytic oxidation of manganate (Vl) |
1 | 4190-4193 | ,
Cr2O7
2– + 14 H
+ + 6 Fe
2+ ® 2 Cr
3+ + 6 Fe
3+ + 7 H2O
Potassium permanganate KMnO4
Potassium permanganate is prepared by fusion of MnO2 with an alkali
metal hydroxide and an oxidising agent like KNO3 This produces the
dark green K2MnO4 which disproportionates in a neutral or acidic
solution to give permanganate 2MnO2 + 4KOH + O2 ® 2K2MnO4 + 2H2O
3MnO4
2– + 4H+ ® 2MnO4
– + MnO2 + 2H2O
Commercially it is prepared by the alkaline oxidative fusion of MnO2
followed by the electrolytic oxidation of manganate (Vl) F
used with KOH, oxidised
with air or KNO
2
3
2
4
MnO
MnO
;
manganate ion
−
→
42
4
Electrolytic oxidation in
alkaline solution
MnO
MnO
manganate
permanganate ion
Rationalised 2023-24
107
The d- and f- Block Elements
In the laboratory, a manganese (II) ion salt is oxidised by
peroxodisulphate to permanganate |
1 | 4191-4194 | This produces the
dark green K2MnO4 which disproportionates in a neutral or acidic
solution to give permanganate 2MnO2 + 4KOH + O2 ® 2K2MnO4 + 2H2O
3MnO4
2– + 4H+ ® 2MnO4
– + MnO2 + 2H2O
Commercially it is prepared by the alkaline oxidative fusion of MnO2
followed by the electrolytic oxidation of manganate (Vl) F
used with KOH, oxidised
with air or KNO
2
3
2
4
MnO
MnO
;
manganate ion
−
→
42
4
Electrolytic oxidation in
alkaline solution
MnO
MnO
manganate
permanganate ion
Rationalised 2023-24
107
The d- and f- Block Elements
In the laboratory, a manganese (II) ion salt is oxidised by
peroxodisulphate to permanganate 2Mn
2+ + 5S2O8
2– + 8H2O ® 2MnO4
– + 10SO4
2– + 16H
+
Potassium permanganate forms dark purple (almost black) crystals which
are isostructural with those of KClO4 |
1 | 4192-4195 | 2MnO2 + 4KOH + O2 ® 2K2MnO4 + 2H2O
3MnO4
2– + 4H+ ® 2MnO4
– + MnO2 + 2H2O
Commercially it is prepared by the alkaline oxidative fusion of MnO2
followed by the electrolytic oxidation of manganate (Vl) F
used with KOH, oxidised
with air or KNO
2
3
2
4
MnO
MnO
;
manganate ion
−
→
42
4
Electrolytic oxidation in
alkaline solution
MnO
MnO
manganate
permanganate ion
Rationalised 2023-24
107
The d- and f- Block Elements
In the laboratory, a manganese (II) ion salt is oxidised by
peroxodisulphate to permanganate 2Mn
2+ + 5S2O8
2– + 8H2O ® 2MnO4
– + 10SO4
2– + 16H
+
Potassium permanganate forms dark purple (almost black) crystals which
are isostructural with those of KClO4 The salt is not very soluble in water
(6 |
1 | 4193-4196 | F
used with KOH, oxidised
with air or KNO
2
3
2
4
MnO
MnO
;
manganate ion
−
→
42
4
Electrolytic oxidation in
alkaline solution
MnO
MnO
manganate
permanganate ion
Rationalised 2023-24
107
The d- and f- Block Elements
In the laboratory, a manganese (II) ion salt is oxidised by
peroxodisulphate to permanganate 2Mn
2+ + 5S2O8
2– + 8H2O ® 2MnO4
– + 10SO4
2– + 16H
+
Potassium permanganate forms dark purple (almost black) crystals which
are isostructural with those of KClO4 The salt is not very soluble in water
(6 4 g/100 g of water at 293 K), but when heated it decomposes at 513 K |
1 | 4194-4197 | 2Mn
2+ + 5S2O8
2– + 8H2O ® 2MnO4
– + 10SO4
2– + 16H
+
Potassium permanganate forms dark purple (almost black) crystals which
are isostructural with those of KClO4 The salt is not very soluble in water
(6 4 g/100 g of water at 293 K), but when heated it decomposes at 513 K 2KMnO4 ® K2MnO4 + MnO2 + O2
It has two physical properties of considerable interest: its intense colour
and its diamagnetism along with temperature-dependent weak
paramagnetism |
1 | 4195-4198 | The salt is not very soluble in water
(6 4 g/100 g of water at 293 K), but when heated it decomposes at 513 K 2KMnO4 ® K2MnO4 + MnO2 + O2
It has two physical properties of considerable interest: its intense colour
and its diamagnetism along with temperature-dependent weak
paramagnetism These can be explained by the use of molecular orbital
theory which is beyond the present scope |
1 | 4196-4199 | 4 g/100 g of water at 293 K), but when heated it decomposes at 513 K 2KMnO4 ® K2MnO4 + MnO2 + O2
It has two physical properties of considerable interest: its intense colour
and its diamagnetism along with temperature-dependent weak
paramagnetism These can be explained by the use of molecular orbital
theory which is beyond the present scope The manganate and permanganate ions are tetrahedral; the p-
bonding takes place by overlap of p orbitals of oxygen with d orbitals
of manganese |
1 | 4197-4200 | 2KMnO4 ® K2MnO4 + MnO2 + O2
It has two physical properties of considerable interest: its intense colour
and its diamagnetism along with temperature-dependent weak
paramagnetism These can be explained by the use of molecular orbital
theory which is beyond the present scope The manganate and permanganate ions are tetrahedral; the p-
bonding takes place by overlap of p orbitals of oxygen with d orbitals
of manganese The green manganate is paramagnetic because of one
unpaired electron but the permanganate is diamagnetic due to the
absence of unpaired electron |
1 | 4198-4201 | These can be explained by the use of molecular orbital
theory which is beyond the present scope The manganate and permanganate ions are tetrahedral; the p-
bonding takes place by overlap of p orbitals of oxygen with d orbitals
of manganese The green manganate is paramagnetic because of one
unpaired electron but the permanganate is diamagnetic due to the
absence of unpaired electron Acidified permanganate solution oxidises oxalates to carbon dioxide,
iron(II) to iron(III), nitrites to nitrates and iodides to free iodine |
1 | 4199-4202 | The manganate and permanganate ions are tetrahedral; the p-
bonding takes place by overlap of p orbitals of oxygen with d orbitals
of manganese The green manganate is paramagnetic because of one
unpaired electron but the permanganate is diamagnetic due to the
absence of unpaired electron Acidified permanganate solution oxidises oxalates to carbon dioxide,
iron(II) to iron(III), nitrites to nitrates and iodides to free iodine The half-reactions of reductants are:
COO
–
COO
–
5
10CO2 + 10e
–
5 Fe2+ ® 5 Fe3+ + 5e–
5NO2
– + 5H2O ® 5NO3
– + 10H+ + l0e–
10I– ® 5I2 + 10e–
The full reaction can be written by adding the half-reaction for
KMnO4 to the half-reaction of the reducing agent, balancing wherever
necessary |
1 | 4200-4203 | The green manganate is paramagnetic because of one
unpaired electron but the permanganate is diamagnetic due to the
absence of unpaired electron Acidified permanganate solution oxidises oxalates to carbon dioxide,
iron(II) to iron(III), nitrites to nitrates and iodides to free iodine The half-reactions of reductants are:
COO
–
COO
–
5
10CO2 + 10e
–
5 Fe2+ ® 5 Fe3+ + 5e–
5NO2
– + 5H2O ® 5NO3
– + 10H+ + l0e–
10I– ® 5I2 + 10e–
The full reaction can be written by adding the half-reaction for
KMnO4 to the half-reaction of the reducing agent, balancing wherever
necessary If we represent the reduction of permanganate to manganate,
manganese dioxide and manganese(II) salt by half-reactions,
MnO4
– + e– ® MnO4
2–
(E
o = + 0 |
1 | 4201-4204 | Acidified permanganate solution oxidises oxalates to carbon dioxide,
iron(II) to iron(III), nitrites to nitrates and iodides to free iodine The half-reactions of reductants are:
COO
–
COO
–
5
10CO2 + 10e
–
5 Fe2+ ® 5 Fe3+ + 5e–
5NO2
– + 5H2O ® 5NO3
– + 10H+ + l0e–
10I– ® 5I2 + 10e–
The full reaction can be written by adding the half-reaction for
KMnO4 to the half-reaction of the reducing agent, balancing wherever
necessary If we represent the reduction of permanganate to manganate,
manganese dioxide and manganese(II) salt by half-reactions,
MnO4
– + e– ® MnO4
2–
(E
o = + 0 56 V)
MnO4
– + 4H+ + 3e– ® MnO2 + 2H2O
(E
o = + 1 |
1 | 4202-4205 | The half-reactions of reductants are:
COO
–
COO
–
5
10CO2 + 10e
–
5 Fe2+ ® 5 Fe3+ + 5e–
5NO2
– + 5H2O ® 5NO3
– + 10H+ + l0e–
10I– ® 5I2 + 10e–
The full reaction can be written by adding the half-reaction for
KMnO4 to the half-reaction of the reducing agent, balancing wherever
necessary If we represent the reduction of permanganate to manganate,
manganese dioxide and manganese(II) salt by half-reactions,
MnO4
– + e– ® MnO4
2–
(E
o = + 0 56 V)
MnO4
– + 4H+ + 3e– ® MnO2 + 2H2O
(E
o = + 1 69 V)
MnO4
– + 8H+ + 5e– ® Mn2+ + 4H2O
(E
o = + 1 |
1 | 4203-4206 | If we represent the reduction of permanganate to manganate,
manganese dioxide and manganese(II) salt by half-reactions,
MnO4
– + e– ® MnO4
2–
(E
o = + 0 56 V)
MnO4
– + 4H+ + 3e– ® MnO2 + 2H2O
(E
o = + 1 69 V)
MnO4
– + 8H+ + 5e– ® Mn2+ + 4H2O
(E
o = + 1 52 V)
We can very well see that the hydrogen ion concentration of the
solution plays an important part in influencing the reaction |
1 | 4204-4207 | 56 V)
MnO4
– + 4H+ + 3e– ® MnO2 + 2H2O
(E
o = + 1 69 V)
MnO4
– + 8H+ + 5e– ® Mn2+ + 4H2O
(E
o = + 1 52 V)
We can very well see that the hydrogen ion concentration of the
solution plays an important part in influencing the reaction Although
many reactions can be understood by consideration of redox potential,
kinetics of the reaction is also an important factor |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.