Selina Textbook Solutions: Study of Compounds - Nitric Acid | Chemistry Class 10 ICSE PDF Download

 Page 1


Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
EXERCISE .1 
 
Question 1:  
What is: (a) aqua fortis, (b) aqua regia (c) Fixation of Nitrogen? 
Solution 1: 
(a) Aqua fortis: Nitric acid is called aqua fortis. Aqua fortis means strong water. It is so called 
because it reacts with nearly all metals. 
(b) Aqua Regia: Conc. Nitric acid (1part by volume) when mixed with conc. Hydrochloric acid 
(3 parts by volume) gives a mixture called aqua regia. It means Royal water. 
      HNO3 + 3HCl ? NOCl + 2H2O + 2[Cl] 
(c) Fixation of Nitrogen: The conversion of free atmospheric nitrogen into useful nitrogenous 
compounds in the soil is known as fixation of atmospheric nitrogen. 
 
 
Question 2:  
During thunderstorm, rain water contains nitric acid. Explain with reactions. 
Solution 2: 
During lightning discharge, the nitrogen present in the atmosphere reacts with oxygen to form 
nitric oxide. 
N2 + O2  2NO 
Nitric oxide is further oxidized to nitrogen dioxide. 
2NO + O2  2NO2 
The nitrogen dioxide dissolves in atmospheric moisture in the presence of oxygen of the air and 
forms nitric acid which is washed down by the rain and combines with the salt present on the 
surface of the earth. 
4NO2 + 2H2O + O2 ? 4HNO3 
 
 
Question 3:  
(a) Write a balanced chemical equation for the laboratory preparation of nitric acid 
(b) In the preparation of nitric acid from KNO3 concentrated hydrochloric acid is not used in 
place of concentrated sulphuric acid. Explain why? 
(c) Conc. Nitric acid prepared in laboratory is yellow in colour why? How is this colour 
removed? 
(d) Give reasons for the following: 
In the laboratory preparation of nitric acid, the mixture of concentrated sulphuric acid and 
sodium nitrate should not be heated very strongly above 200
°
C. 
 
Page 2


Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
EXERCISE .1 
 
Question 1:  
What is: (a) aqua fortis, (b) aqua regia (c) Fixation of Nitrogen? 
Solution 1: 
(a) Aqua fortis: Nitric acid is called aqua fortis. Aqua fortis means strong water. It is so called 
because it reacts with nearly all metals. 
(b) Aqua Regia: Conc. Nitric acid (1part by volume) when mixed with conc. Hydrochloric acid 
(3 parts by volume) gives a mixture called aqua regia. It means Royal water. 
      HNO3 + 3HCl ? NOCl + 2H2O + 2[Cl] 
(c) Fixation of Nitrogen: The conversion of free atmospheric nitrogen into useful nitrogenous 
compounds in the soil is known as fixation of atmospheric nitrogen. 
 
 
Question 2:  
During thunderstorm, rain water contains nitric acid. Explain with reactions. 
Solution 2: 
During lightning discharge, the nitrogen present in the atmosphere reacts with oxygen to form 
nitric oxide. 
N2 + O2  2NO 
Nitric oxide is further oxidized to nitrogen dioxide. 
2NO + O2  2NO2 
The nitrogen dioxide dissolves in atmospheric moisture in the presence of oxygen of the air and 
forms nitric acid which is washed down by the rain and combines with the salt present on the 
surface of the earth. 
4NO2 + 2H2O + O2 ? 4HNO3 
 
 
Question 3:  
(a) Write a balanced chemical equation for the laboratory preparation of nitric acid 
(b) In the preparation of nitric acid from KNO3 concentrated hydrochloric acid is not used in 
place of concentrated sulphuric acid. Explain why? 
(c) Conc. Nitric acid prepared in laboratory is yellow in colour why? How is this colour 
removed? 
(d) Give reasons for the following: 
In the laboratory preparation of nitric acid, the mixture of concentrated sulphuric acid and 
sodium nitrate should not be heated very strongly above 200
°
C. 
 
Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
Solution 3: 
(a) Chemical equation is: 
      KNO3 + H2SO4 
0
 200 C ?
? ? ? ? KHSO4 + HNO3 
(b) Concentrated hydrochloric acid cannot replace Conc. Sulphuric acid for the preparation of 
nitric acid because hydrochloric acid is volatile acid and hence nitric acid vapours will carry 
HCl vapours. 
(c) Conc. Nitric acid prepared in the laboratory is yellow in colour due to the dissolution of 
reddish brown coloured nitrogen dioxide gas in acid. This gas is produced due to the thermal 
dissociation of a portion of nitric acid. 
      4HNO3 2H2O + 4NO2 + O2 
The yellow colour of the acid is removed: 
If dry air or CO2 is bubbled through the yellow acid, the acid turns colourless because it 
drives out NO2 from warm acid which is further oxidized to nitric acid. 
By addition of excess of water, nitrogen dioxide gas dissolves in water and thus the yellow 
colour of the acid is removed. 
(d) The temperature of the mixture of concentrated sulphuric acid and sodium nitrate should not 
exceed 200
o
C because sodium sulphate formed at higher temperature forms a hard crust 
which sticks to the walls of the retort and is difficult to remove. At higher temperature nitric 
acid may also decompose. 
      NaNO3 + NaHSO4 
0
200 C ?
? ? ? ? Na2SO4 + HNO3 
 
 
Question 4:  
Nitric acid cannot be concentrated beyond 68% by the distillation of a dilute solution of HNO3 
State the reason. 
Solution 4: 
Nitric acid forms a constant boiling mixture with water containing 68% acid. This mixture boils 
constantly at constant boiling point without any change in its composition. At this temperature, 
the gas and the water vapour escape together. Hence the composition of the solution remains 
unchanged. So nitric acid cannot be concentrated beyond 68% by distillation of dilute solution 
of HNO3. 
 
 
Question 5:  
What is passive iron? How is passivity removed? 
Solution 5: 
Iron becomes inert when reacted with nitric acid due to the formation of extremely thin layer of 
insoluble metallic oxide which stops the reaction. 
Passivity can be removed by rubbing the surface layer with the sand paper or by treating with 
strong reducing agent. 
 
Page 3


Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
EXERCISE .1 
 
Question 1:  
What is: (a) aqua fortis, (b) aqua regia (c) Fixation of Nitrogen? 
Solution 1: 
(a) Aqua fortis: Nitric acid is called aqua fortis. Aqua fortis means strong water. It is so called 
because it reacts with nearly all metals. 
(b) Aqua Regia: Conc. Nitric acid (1part by volume) when mixed with conc. Hydrochloric acid 
(3 parts by volume) gives a mixture called aqua regia. It means Royal water. 
      HNO3 + 3HCl ? NOCl + 2H2O + 2[Cl] 
(c) Fixation of Nitrogen: The conversion of free atmospheric nitrogen into useful nitrogenous 
compounds in the soil is known as fixation of atmospheric nitrogen. 
 
 
Question 2:  
During thunderstorm, rain water contains nitric acid. Explain with reactions. 
Solution 2: 
During lightning discharge, the nitrogen present in the atmosphere reacts with oxygen to form 
nitric oxide. 
N2 + O2  2NO 
Nitric oxide is further oxidized to nitrogen dioxide. 
2NO + O2  2NO2 
The nitrogen dioxide dissolves in atmospheric moisture in the presence of oxygen of the air and 
forms nitric acid which is washed down by the rain and combines with the salt present on the 
surface of the earth. 
4NO2 + 2H2O + O2 ? 4HNO3 
 
 
Question 3:  
(a) Write a balanced chemical equation for the laboratory preparation of nitric acid 
(b) In the preparation of nitric acid from KNO3 concentrated hydrochloric acid is not used in 
place of concentrated sulphuric acid. Explain why? 
(c) Conc. Nitric acid prepared in laboratory is yellow in colour why? How is this colour 
removed? 
(d) Give reasons for the following: 
In the laboratory preparation of nitric acid, the mixture of concentrated sulphuric acid and 
sodium nitrate should not be heated very strongly above 200
°
C. 
 
Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
Solution 3: 
(a) Chemical equation is: 
      KNO3 + H2SO4 
0
 200 C ?
? ? ? ? KHSO4 + HNO3 
(b) Concentrated hydrochloric acid cannot replace Conc. Sulphuric acid for the preparation of 
nitric acid because hydrochloric acid is volatile acid and hence nitric acid vapours will carry 
HCl vapours. 
(c) Conc. Nitric acid prepared in the laboratory is yellow in colour due to the dissolution of 
reddish brown coloured nitrogen dioxide gas in acid. This gas is produced due to the thermal 
dissociation of a portion of nitric acid. 
      4HNO3 2H2O + 4NO2 + O2 
The yellow colour of the acid is removed: 
If dry air or CO2 is bubbled through the yellow acid, the acid turns colourless because it 
drives out NO2 from warm acid which is further oxidized to nitric acid. 
By addition of excess of water, nitrogen dioxide gas dissolves in water and thus the yellow 
colour of the acid is removed. 
(d) The temperature of the mixture of concentrated sulphuric acid and sodium nitrate should not 
exceed 200
o
C because sodium sulphate formed at higher temperature forms a hard crust 
which sticks to the walls of the retort and is difficult to remove. At higher temperature nitric 
acid may also decompose. 
      NaNO3 + NaHSO4 
0
200 C ?
? ? ? ? Na2SO4 + HNO3 
 
 
Question 4:  
Nitric acid cannot be concentrated beyond 68% by the distillation of a dilute solution of HNO3 
State the reason. 
Solution 4: 
Nitric acid forms a constant boiling mixture with water containing 68% acid. This mixture boils 
constantly at constant boiling point without any change in its composition. At this temperature, 
the gas and the water vapour escape together. Hence the composition of the solution remains 
unchanged. So nitric acid cannot be concentrated beyond 68% by distillation of dilute solution 
of HNO3. 
 
 
Question 5:  
What is passive iron? How is passivity removed? 
Solution 5: 
Iron becomes inert when reacted with nitric acid due to the formation of extremely thin layer of 
insoluble metallic oxide which stops the reaction. 
Passivity can be removed by rubbing the surface layer with the sand paper or by treating with 
strong reducing agent. 
 
Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
Question 6:  
Name the products formed when: 
(a) carbon and conc. Nitric acid is heated 
(b) dilute HNO3 is added to copper. 
Solution 6: 
(a) When carbon and conc. Nitric acid is heated the products formed are Carbon dioxide, 
Nitrogen dioxide and water. 
            C + 4HNO3 ? CO2 + 2H2O +4NO2 
(b) Copper when reacts with dilute HNO3 forms Copper nitrate, Nitric oxide and water. 
       3Cu + 8HNO3 ? 3Cu(NO3) 2 + 4H2O + 2NO 
 
 
Question 7:  
Give two chemical equations for each of the following: 
(a) Reactions of nitric acid with non-metals 
(b) Nitric acid showing as acidic character 
(c) Nitric acid acting as oxidizing agent 
Solution 7: 
(a) Reaction of nitric acid with non-metals: 
C + 4HNO3 ? CO2 + 2H2O + 4 NO2 
S + 6 HNO3 ? H2SO4 + 2H2O + 6 NO2 
(b) Nitric acid showing acidic character: 
K2O + 2HNO3 ? 2KNO3 + H2O 
ZnO + 2HNO3 ? Zn(NO3)2 + H2O 
(c) Nitric acid acting as oxidizing agent 
P4 +20HNO3 ? 4H3PO4 + 4H2O + 20NO2 
3Zn +8HNO3 ? 3Zn(NO3)2 + 4H2O + 2NO 
 
 
Question 8:  
Write balanced equations and name the products formed when: 
(a) Sodium hydrogen carbonate is added to nitric acid 
(b) cupric oxide reacts with nitric acid 
(c) zinc reacts with dilute nitric acid 
(d) concentrated nitric acid is heated 
Solution 8: 
(a) When Sodium hydrogen carbonate is added to nitric acid sodium nitrate, carbon dioxide and 
water is formed. 
       NaHCO3 + HNO3 ? NaNO3 + H2O + CO2  
(b) When Cupric oxide reacts with dilute nitric acid, it forms Copper nitrate. 
Page 4


Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
EXERCISE .1 
 
Question 1:  
What is: (a) aqua fortis, (b) aqua regia (c) Fixation of Nitrogen? 
Solution 1: 
(a) Aqua fortis: Nitric acid is called aqua fortis. Aqua fortis means strong water. It is so called 
because it reacts with nearly all metals. 
(b) Aqua Regia: Conc. Nitric acid (1part by volume) when mixed with conc. Hydrochloric acid 
(3 parts by volume) gives a mixture called aqua regia. It means Royal water. 
      HNO3 + 3HCl ? NOCl + 2H2O + 2[Cl] 
(c) Fixation of Nitrogen: The conversion of free atmospheric nitrogen into useful nitrogenous 
compounds in the soil is known as fixation of atmospheric nitrogen. 
 
 
Question 2:  
During thunderstorm, rain water contains nitric acid. Explain with reactions. 
Solution 2: 
During lightning discharge, the nitrogen present in the atmosphere reacts with oxygen to form 
nitric oxide. 
N2 + O2  2NO 
Nitric oxide is further oxidized to nitrogen dioxide. 
2NO + O2  2NO2 
The nitrogen dioxide dissolves in atmospheric moisture in the presence of oxygen of the air and 
forms nitric acid which is washed down by the rain and combines with the salt present on the 
surface of the earth. 
4NO2 + 2H2O + O2 ? 4HNO3 
 
 
Question 3:  
(a) Write a balanced chemical equation for the laboratory preparation of nitric acid 
(b) In the preparation of nitric acid from KNO3 concentrated hydrochloric acid is not used in 
place of concentrated sulphuric acid. Explain why? 
(c) Conc. Nitric acid prepared in laboratory is yellow in colour why? How is this colour 
removed? 
(d) Give reasons for the following: 
In the laboratory preparation of nitric acid, the mixture of concentrated sulphuric acid and 
sodium nitrate should not be heated very strongly above 200
°
C. 
 
Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
Solution 3: 
(a) Chemical equation is: 
      KNO3 + H2SO4 
0
 200 C ?
? ? ? ? KHSO4 + HNO3 
(b) Concentrated hydrochloric acid cannot replace Conc. Sulphuric acid for the preparation of 
nitric acid because hydrochloric acid is volatile acid and hence nitric acid vapours will carry 
HCl vapours. 
(c) Conc. Nitric acid prepared in the laboratory is yellow in colour due to the dissolution of 
reddish brown coloured nitrogen dioxide gas in acid. This gas is produced due to the thermal 
dissociation of a portion of nitric acid. 
      4HNO3 2H2O + 4NO2 + O2 
The yellow colour of the acid is removed: 
If dry air or CO2 is bubbled through the yellow acid, the acid turns colourless because it 
drives out NO2 from warm acid which is further oxidized to nitric acid. 
By addition of excess of water, nitrogen dioxide gas dissolves in water and thus the yellow 
colour of the acid is removed. 
(d) The temperature of the mixture of concentrated sulphuric acid and sodium nitrate should not 
exceed 200
o
C because sodium sulphate formed at higher temperature forms a hard crust 
which sticks to the walls of the retort and is difficult to remove. At higher temperature nitric 
acid may also decompose. 
      NaNO3 + NaHSO4 
0
200 C ?
? ? ? ? Na2SO4 + HNO3 
 
 
Question 4:  
Nitric acid cannot be concentrated beyond 68% by the distillation of a dilute solution of HNO3 
State the reason. 
Solution 4: 
Nitric acid forms a constant boiling mixture with water containing 68% acid. This mixture boils 
constantly at constant boiling point without any change in its composition. At this temperature, 
the gas and the water vapour escape together. Hence the composition of the solution remains 
unchanged. So nitric acid cannot be concentrated beyond 68% by distillation of dilute solution 
of HNO3. 
 
 
Question 5:  
What is passive iron? How is passivity removed? 
Solution 5: 
Iron becomes inert when reacted with nitric acid due to the formation of extremely thin layer of 
insoluble metallic oxide which stops the reaction. 
Passivity can be removed by rubbing the surface layer with the sand paper or by treating with 
strong reducing agent. 
 
Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
Question 6:  
Name the products formed when: 
(a) carbon and conc. Nitric acid is heated 
(b) dilute HNO3 is added to copper. 
Solution 6: 
(a) When carbon and conc. Nitric acid is heated the products formed are Carbon dioxide, 
Nitrogen dioxide and water. 
            C + 4HNO3 ? CO2 + 2H2O +4NO2 
(b) Copper when reacts with dilute HNO3 forms Copper nitrate, Nitric oxide and water. 
       3Cu + 8HNO3 ? 3Cu(NO3) 2 + 4H2O + 2NO 
 
 
Question 7:  
Give two chemical equations for each of the following: 
(a) Reactions of nitric acid with non-metals 
(b) Nitric acid showing as acidic character 
(c) Nitric acid acting as oxidizing agent 
Solution 7: 
(a) Reaction of nitric acid with non-metals: 
C + 4HNO3 ? CO2 + 2H2O + 4 NO2 
S + 6 HNO3 ? H2SO4 + 2H2O + 6 NO2 
(b) Nitric acid showing acidic character: 
K2O + 2HNO3 ? 2KNO3 + H2O 
ZnO + 2HNO3 ? Zn(NO3)2 + H2O 
(c) Nitric acid acting as oxidizing agent 
P4 +20HNO3 ? 4H3PO4 + 4H2O + 20NO2 
3Zn +8HNO3 ? 3Zn(NO3)2 + 4H2O + 2NO 
 
 
Question 8:  
Write balanced equations and name the products formed when: 
(a) Sodium hydrogen carbonate is added to nitric acid 
(b) cupric oxide reacts with nitric acid 
(c) zinc reacts with dilute nitric acid 
(d) concentrated nitric acid is heated 
Solution 8: 
(a) When Sodium hydrogen carbonate is added to nitric acid sodium nitrate, carbon dioxide and 
water is formed. 
       NaHCO3 + HNO3 ? NaNO3 + H2O + CO2  
(b) When Cupric oxide reacts with dilute nitric acid, it forms Copper nitrate. 
Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
      CuO + 2HNO3 ? Cu(NO3)2 + H2O 
(c) Zinc reacts with nitric acid to form Zinc nitrate, nitric oxide and water. 
      3 Zn + 8HNO3 ? 3Zn(NO3)2 + 4H2O + 2NO 
(d) 4HNO3 ? 2H2O + 4NO2 + O2 
 
 
Question 9:  
Write equation for the following conversions A, B, C and D. 
 
Solution 9: 
A: Copper can be converted into copper nitrate. 
     3Cu + 8HNO3 ? 3Cu(NO3)2 + 4H2O + 2NO 
B: 2Cu(NO3)2 
?
? ? ? 2CuO + 4NO2 + O2 
C: 2Cu + O2 
?
? ? ? 2CuO 
D: By reduction 
     2CuO + C ? 2Cu + CO2 
 
 
Question 10:  
How will you prepare the following from nitric acid? 
(a) Sodium nitrate     (b) copper nitrate 
(c) Lead nitrate         (d) Magnesium nitrate 
(e) Ferric nitrate        (f) Aqua regia 
Solution 10: 
(a) Sodium nitrate: 
NaOH + HNO3 ? NaNO3 + H2O 
Sodium hydroxide reacts with nitric acid to form sodium nitrate. 
(b) Copper nitrate: 
      CuO + 2HNO3 ? Cu(NO3)2 + H2O 
      Copper oxide reacts with nitric acid to form copper nitrate. 
(c) Lead nitrate: 
      Pb + 4HNO3 ? Pb(NO3)2 + 2H2O + 2NO2 
      Lead reacts with conc. nitric acid to form lead nitrate.  
(d) Magnesium nitrate: 
Mg + 2HNO3 ? Mg(NO3)2 + H2 
Magnesium with dil. nitric acid to form magnesium nitrate. 
(e) Ferric nitrate: 
Fe + 6HNO3 ? Fe(NO3)3 + 3H2O + 3NO2 
Page 5


Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
EXERCISE .1 
 
Question 1:  
What is: (a) aqua fortis, (b) aqua regia (c) Fixation of Nitrogen? 
Solution 1: 
(a) Aqua fortis: Nitric acid is called aqua fortis. Aqua fortis means strong water. It is so called 
because it reacts with nearly all metals. 
(b) Aqua Regia: Conc. Nitric acid (1part by volume) when mixed with conc. Hydrochloric acid 
(3 parts by volume) gives a mixture called aqua regia. It means Royal water. 
      HNO3 + 3HCl ? NOCl + 2H2O + 2[Cl] 
(c) Fixation of Nitrogen: The conversion of free atmospheric nitrogen into useful nitrogenous 
compounds in the soil is known as fixation of atmospheric nitrogen. 
 
 
Question 2:  
During thunderstorm, rain water contains nitric acid. Explain with reactions. 
Solution 2: 
During lightning discharge, the nitrogen present in the atmosphere reacts with oxygen to form 
nitric oxide. 
N2 + O2  2NO 
Nitric oxide is further oxidized to nitrogen dioxide. 
2NO + O2  2NO2 
The nitrogen dioxide dissolves in atmospheric moisture in the presence of oxygen of the air and 
forms nitric acid which is washed down by the rain and combines with the salt present on the 
surface of the earth. 
4NO2 + 2H2O + O2 ? 4HNO3 
 
 
Question 3:  
(a) Write a balanced chemical equation for the laboratory preparation of nitric acid 
(b) In the preparation of nitric acid from KNO3 concentrated hydrochloric acid is not used in 
place of concentrated sulphuric acid. Explain why? 
(c) Conc. Nitric acid prepared in laboratory is yellow in colour why? How is this colour 
removed? 
(d) Give reasons for the following: 
In the laboratory preparation of nitric acid, the mixture of concentrated sulphuric acid and 
sodium nitrate should not be heated very strongly above 200
°
C. 
 
Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
Solution 3: 
(a) Chemical equation is: 
      KNO3 + H2SO4 
0
 200 C ?
? ? ? ? KHSO4 + HNO3 
(b) Concentrated hydrochloric acid cannot replace Conc. Sulphuric acid for the preparation of 
nitric acid because hydrochloric acid is volatile acid and hence nitric acid vapours will carry 
HCl vapours. 
(c) Conc. Nitric acid prepared in the laboratory is yellow in colour due to the dissolution of 
reddish brown coloured nitrogen dioxide gas in acid. This gas is produced due to the thermal 
dissociation of a portion of nitric acid. 
      4HNO3 2H2O + 4NO2 + O2 
The yellow colour of the acid is removed: 
If dry air or CO2 is bubbled through the yellow acid, the acid turns colourless because it 
drives out NO2 from warm acid which is further oxidized to nitric acid. 
By addition of excess of water, nitrogen dioxide gas dissolves in water and thus the yellow 
colour of the acid is removed. 
(d) The temperature of the mixture of concentrated sulphuric acid and sodium nitrate should not 
exceed 200
o
C because sodium sulphate formed at higher temperature forms a hard crust 
which sticks to the walls of the retort and is difficult to remove. At higher temperature nitric 
acid may also decompose. 
      NaNO3 + NaHSO4 
0
200 C ?
? ? ? ? Na2SO4 + HNO3 
 
 
Question 4:  
Nitric acid cannot be concentrated beyond 68% by the distillation of a dilute solution of HNO3 
State the reason. 
Solution 4: 
Nitric acid forms a constant boiling mixture with water containing 68% acid. This mixture boils 
constantly at constant boiling point without any change in its composition. At this temperature, 
the gas and the water vapour escape together. Hence the composition of the solution remains 
unchanged. So nitric acid cannot be concentrated beyond 68% by distillation of dilute solution 
of HNO3. 
 
 
Question 5:  
What is passive iron? How is passivity removed? 
Solution 5: 
Iron becomes inert when reacted with nitric acid due to the formation of extremely thin layer of 
insoluble metallic oxide which stops the reaction. 
Passivity can be removed by rubbing the surface layer with the sand paper or by treating with 
strong reducing agent. 
 
Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
Question 6:  
Name the products formed when: 
(a) carbon and conc. Nitric acid is heated 
(b) dilute HNO3 is added to copper. 
Solution 6: 
(a) When carbon and conc. Nitric acid is heated the products formed are Carbon dioxide, 
Nitrogen dioxide and water. 
            C + 4HNO3 ? CO2 + 2H2O +4NO2 
(b) Copper when reacts with dilute HNO3 forms Copper nitrate, Nitric oxide and water. 
       3Cu + 8HNO3 ? 3Cu(NO3) 2 + 4H2O + 2NO 
 
 
Question 7:  
Give two chemical equations for each of the following: 
(a) Reactions of nitric acid with non-metals 
(b) Nitric acid showing as acidic character 
(c) Nitric acid acting as oxidizing agent 
Solution 7: 
(a) Reaction of nitric acid with non-metals: 
C + 4HNO3 ? CO2 + 2H2O + 4 NO2 
S + 6 HNO3 ? H2SO4 + 2H2O + 6 NO2 
(b) Nitric acid showing acidic character: 
K2O + 2HNO3 ? 2KNO3 + H2O 
ZnO + 2HNO3 ? Zn(NO3)2 + H2O 
(c) Nitric acid acting as oxidizing agent 
P4 +20HNO3 ? 4H3PO4 + 4H2O + 20NO2 
3Zn +8HNO3 ? 3Zn(NO3)2 + 4H2O + 2NO 
 
 
Question 8:  
Write balanced equations and name the products formed when: 
(a) Sodium hydrogen carbonate is added to nitric acid 
(b) cupric oxide reacts with nitric acid 
(c) zinc reacts with dilute nitric acid 
(d) concentrated nitric acid is heated 
Solution 8: 
(a) When Sodium hydrogen carbonate is added to nitric acid sodium nitrate, carbon dioxide and 
water is formed. 
       NaHCO3 + HNO3 ? NaNO3 + H2O + CO2  
(b) When Cupric oxide reacts with dilute nitric acid, it forms Copper nitrate. 
Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
      CuO + 2HNO3 ? Cu(NO3)2 + H2O 
(c) Zinc reacts with nitric acid to form Zinc nitrate, nitric oxide and water. 
      3 Zn + 8HNO3 ? 3Zn(NO3)2 + 4H2O + 2NO 
(d) 4HNO3 ? 2H2O + 4NO2 + O2 
 
 
Question 9:  
Write equation for the following conversions A, B, C and D. 
 
Solution 9: 
A: Copper can be converted into copper nitrate. 
     3Cu + 8HNO3 ? 3Cu(NO3)2 + 4H2O + 2NO 
B: 2Cu(NO3)2 
?
? ? ? 2CuO + 4NO2 + O2 
C: 2Cu + O2 
?
? ? ? 2CuO 
D: By reduction 
     2CuO + C ? 2Cu + CO2 
 
 
Question 10:  
How will you prepare the following from nitric acid? 
(a) Sodium nitrate     (b) copper nitrate 
(c) Lead nitrate         (d) Magnesium nitrate 
(e) Ferric nitrate        (f) Aqua regia 
Solution 10: 
(a) Sodium nitrate: 
NaOH + HNO3 ? NaNO3 + H2O 
Sodium hydroxide reacts with nitric acid to form sodium nitrate. 
(b) Copper nitrate: 
      CuO + 2HNO3 ? Cu(NO3)2 + H2O 
      Copper oxide reacts with nitric acid to form copper nitrate. 
(c) Lead nitrate: 
      Pb + 4HNO3 ? Pb(NO3)2 + 2H2O + 2NO2 
      Lead reacts with conc. nitric acid to form lead nitrate.  
(d) Magnesium nitrate: 
Mg + 2HNO3 ? Mg(NO3)2 + H2 
Magnesium with dil. nitric acid to form magnesium nitrate. 
(e) Ferric nitrate: 
Fe + 6HNO3 ? Fe(NO3)3 + 3H2O + 3NO2 
Class X Chapter 10 – Nitric Acid Chemistry 
_____________________________________________________________________________ 
 
Iron reacts with conc. nitric acid to form ferric nitrate. 
(f) Aqua regia: 
HNO3 + 3HCl ? NOCl + 2H2O + 2[Cl] 
Nitric acid reacts with hydrochloric acid to form a mixture called aqua regia. 
 
 
Question 11:  
Correct the following, if required: 
(a) HNO3 is strong reducing agent. 
(b) NaNO3 gives Na2 and O2 on heating. 
(c) Constant boiling nitric acid contains 80% nitric acid by weight. 
(d) Nitric acid remains colourless even when exposed to light. 
Solution 11: 
(a) HNO3 is strong oxidizing agent. 
(b) NaNO3 gives NaNO2 and oxygen on heating. 
(c) Constant boiling nitric acid contains 68% nitric acid by weight. 
(d) Nitric acid turns yellow solution when exposed to light. 
 
 
Question 12:  
Name: 
(a) a nitrate of metal which on heating does not give nitrogen dioxide  
(b) a nitrate which on heating leaves no residue behind. 
(c) a metal nitrate which on heating is changed into metal oxide 
(d) a metal nitrate which on heating is changed into metal 
(e) a solution which absorbs nitric oxide 
(f) the oxide of nitrogen which turns brown on exposure to air. How is it prepared? 
Solution 12: 
(a) Sodium nitrate 
      2NaNO3 
?
? ? ? 2NaNO2 +O2 
(b) A nitrate which on heating leaves no residue behind- Ammonium nitrate. 
(c) A metal nitrate which on heating is changed into metal oxide- Calcium nitrate 
(d) A metal nitrate which on heating is changed into metal- Silver nitrate 
(e) A solution which absorbs nitric oxide- Freshly prepared ferrous sulphate 
(f) The oxide of nitrogen which turns brown on exposure to air. - nitric oxide 
       By catalytic oxidation of ammonia.   
    4 NH3 + 5 O2 
0
Pt
800 C
? ? ? ? 4NO + 6 H2O + Heat