Selina Textbook Solutions: Study of Compounds – Sulphuric Acid

 Page 1


Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
Top tutor. 
 
Question 1:  
Comment, sulphuric acid is referred to as: 
(a) King of chemicals                                    (b) Oil of vitriol 
Solution 1: 
(a) Sulphuric acid is called King of Chemicals because there is no other manufactured  
       compound which is used by such a large number of key industries. 
(b) Sulphuric acid is referred to as Oil of vitriol as it was obtained as an oily viscous liquid by  
      heating crystals of green vitriol. 
 
 
Question 2:  
Sulphuric acid is manufactured by contact process 
(a) Give two balanced equations to obtain SO2 in this process. 
(b) Give the conditions for the oxidation of SO2 
Solution 2: 
(a) Two balanced equations to obtain SO2 is: 
(i) 
2 2 2 3 2
4FeS + 11O  2Fe O + 8SO ?  
(ii) S + O2 ? SO2 
(b) The conditions for the oxidation of SO2 are: 
(i) The temperature should be as low as possible. The yield has been found to be maximum 
at about 410
0
C - 450
o
C 
(ii) High pressure (2 atm) is favoured because the product formed has less volume than 
reactant. 
(iii) Excess of oxygen increases the production of sulphur trioxide. 
(iv) Vanadium pentoxide or platinised asbestos is used as catalyst. 
(c) Sulphuric acid is not obtained directly by reacting SO3 with water because the reaction is 
highly exothermic which produce the fine misty droplets of sulphuric acid that is not directly 
absorbed by water. 
(d) The chemical used to dissolve SO3 is concentrated sulphuric acid. The product formed is 
oleum. 
(e) Main reactions of this process are: 
22
S O SO ?? 
2S
VO
2 2 3
450 C
2SO O 2SO ? 
3 2 4 2 2 7
2 2 7 2 2 4
SO H SO H S O
H S O H O 2H SO
??
??
 
 
 
Page 2


Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
Top tutor. 
 
Question 1:  
Comment, sulphuric acid is referred to as: 
(a) King of chemicals                                    (b) Oil of vitriol 
Solution 1: 
(a) Sulphuric acid is called King of Chemicals because there is no other manufactured  
       compound which is used by such a large number of key industries. 
(b) Sulphuric acid is referred to as Oil of vitriol as it was obtained as an oily viscous liquid by  
      heating crystals of green vitriol. 
 
 
Question 2:  
Sulphuric acid is manufactured by contact process 
(a) Give two balanced equations to obtain SO2 in this process. 
(b) Give the conditions for the oxidation of SO2 
Solution 2: 
(a) Two balanced equations to obtain SO2 is: 
(i) 
2 2 2 3 2
4FeS + 11O  2Fe O + 8SO ?  
(ii) S + O2 ? SO2 
(b) The conditions for the oxidation of SO2 are: 
(i) The temperature should be as low as possible. The yield has been found to be maximum 
at about 410
0
C - 450
o
C 
(ii) High pressure (2 atm) is favoured because the product formed has less volume than 
reactant. 
(iii) Excess of oxygen increases the production of sulphur trioxide. 
(iv) Vanadium pentoxide or platinised asbestos is used as catalyst. 
(c) Sulphuric acid is not obtained directly by reacting SO3 with water because the reaction is 
highly exothermic which produce the fine misty droplets of sulphuric acid that is not directly 
absorbed by water. 
(d) The chemical used to dissolve SO3 is concentrated sulphuric acid. The product formed is 
oleum. 
(e) Main reactions of this process are: 
22
S O SO ?? 
2S
VO
2 2 3
450 C
2SO O 2SO ? 
3 2 4 2 2 7
2 2 7 2 2 4
SO H SO H S O
H S O H O 2H SO
??
??
 
 
 
Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
 
Top tutor. 
Question 3:  
Why is water not added to concentrated H2SO4 in order to dilute it? 
Solution 3: 
Water is not added to concentrated acid since it is an exothermic reaction. If water is added to 
the acid, there is a sudden increase in temperature and the acid being in bulk tends to spurt out 
with serious consequences. 
 
 
Question 4:  
Why the impurity of arsenic oxide must be removed before passing the mixture of SO4 and air 
through the catalytic chamber? 
Solution 4: 
Impurity of ARSENIC poisons the catalyst [i.e. deactivates the catalyst]. So, it must be removed 
before passing the mixture of SO2 air through the catalytic chamber. 
 
 
Question 5:  
Give two balanced reactions of each type to show the following properties of sulphuric acid: 
(a) Acidic nature.              (b) Oxidising agent, 
(c) Hygroscopic nature,     (d) Non-volatile nature 
Solution 5: 
Balanced reactions are: 
(a) (a) Acidic nature: 
(i) Dilute H2SO4 reacts with basic oxides to form sulphate and water. 
     2 NaOH + H2SO4 ?Na2SO4 + 2H2O 
(ii) CuO + H2SO4 ? CuSO4 + H2O 
(iii) It reacts with carbonate to produce CO2. 
       Na2CO3 + H2SO4 ?Na2SO4 + H2O + CO2 ? 
(b) Oxidising agent: 
H2SO4 ?H2O +SO2 + [O] 
Nascent oxygen oxidizes non-metals, metals and inorganic compounds. 
For example, 
Carbon to carbon dioxide 
C+H2SO4 ? CO2 +H2O +2SO2 
Sulphur to sulphur dioxide 
S +H2SO4 ? 3SO2 +2H2O 
Page 3


Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
Top tutor. 
 
Question 1:  
Comment, sulphuric acid is referred to as: 
(a) King of chemicals                                    (b) Oil of vitriol 
Solution 1: 
(a) Sulphuric acid is called King of Chemicals because there is no other manufactured  
       compound which is used by such a large number of key industries. 
(b) Sulphuric acid is referred to as Oil of vitriol as it was obtained as an oily viscous liquid by  
      heating crystals of green vitriol. 
 
 
Question 2:  
Sulphuric acid is manufactured by contact process 
(a) Give two balanced equations to obtain SO2 in this process. 
(b) Give the conditions for the oxidation of SO2 
Solution 2: 
(a) Two balanced equations to obtain SO2 is: 
(i) 
2 2 2 3 2
4FeS + 11O  2Fe O + 8SO ?  
(ii) S + O2 ? SO2 
(b) The conditions for the oxidation of SO2 are: 
(i) The temperature should be as low as possible. The yield has been found to be maximum 
at about 410
0
C - 450
o
C 
(ii) High pressure (2 atm) is favoured because the product formed has less volume than 
reactant. 
(iii) Excess of oxygen increases the production of sulphur trioxide. 
(iv) Vanadium pentoxide or platinised asbestos is used as catalyst. 
(c) Sulphuric acid is not obtained directly by reacting SO3 with water because the reaction is 
highly exothermic which produce the fine misty droplets of sulphuric acid that is not directly 
absorbed by water. 
(d) The chemical used to dissolve SO3 is concentrated sulphuric acid. The product formed is 
oleum. 
(e) Main reactions of this process are: 
22
S O SO ?? 
2S
VO
2 2 3
450 C
2SO O 2SO ? 
3 2 4 2 2 7
2 2 7 2 2 4
SO H SO H S O
H S O H O 2H SO
??
??
 
 
 
Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
 
Top tutor. 
Question 3:  
Why is water not added to concentrated H2SO4 in order to dilute it? 
Solution 3: 
Water is not added to concentrated acid since it is an exothermic reaction. If water is added to 
the acid, there is a sudden increase in temperature and the acid being in bulk tends to spurt out 
with serious consequences. 
 
 
Question 4:  
Why the impurity of arsenic oxide must be removed before passing the mixture of SO4 and air 
through the catalytic chamber? 
Solution 4: 
Impurity of ARSENIC poisons the catalyst [i.e. deactivates the catalyst]. So, it must be removed 
before passing the mixture of SO2 air through the catalytic chamber. 
 
 
Question 5:  
Give two balanced reactions of each type to show the following properties of sulphuric acid: 
(a) Acidic nature.              (b) Oxidising agent, 
(c) Hygroscopic nature,     (d) Non-volatile nature 
Solution 5: 
Balanced reactions are: 
(a) (a) Acidic nature: 
(i) Dilute H2SO4 reacts with basic oxides to form sulphate and water. 
     2 NaOH + H2SO4 ?Na2SO4 + 2H2O 
(ii) CuO + H2SO4 ? CuSO4 + H2O 
(iii) It reacts with carbonate to produce CO2. 
       Na2CO3 + H2SO4 ?Na2SO4 + H2O + CO2 ? 
(b) Oxidising agent: 
H2SO4 ?H2O +SO2 + [O] 
Nascent oxygen oxidizes non-metals, metals and inorganic compounds. 
For example, 
Carbon to carbon dioxide 
C+H2SO4 ? CO2 +H2O +2SO2 
Sulphur to sulphur dioxide 
S +H2SO4 ? 3SO2 +2H2O 
Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
 
Top tutor. 
(c) Hygroscopic nature: 
       It has great affinity for water. It readily absorbs moisture from atmospheric air. 
HCOOH 
24
conc.H SO
? ? ? ? ?CO + H2O 
C6H12O6 
24
conc.H SO
? ? ? ? ? 6C + 6H2O 
(d) Non-volatile nature: 
It has a high boiling point (356
o
C) so it is considered to be non-volatile. Therefore, it is used 
for preparing volatile acids like hydrochloric acid, nitric acid from their salts by double 
decomposition reaction. 
NaCl + H2SO4 ?NaHSO4 + HCl 
KCl + H2SO4 ? KHSO4 + HCl 
 
 
Question 6:  
Give a chemical test to distinguish between: 
(a) dilute sulphuric acid and dilute hydrochloric acid 
(b) dilute sulphuric acid and conc. Sulphuric acid 
Solution 6: 
(a) Bring a glass rod dipped in Ammonia solution near the mouth of each test tubes containing 
dil. Hel and dil. H2SO4each. 
Dil HCl Dil. H2SO4 
White fumes of ammonium 
chloride 
No such fumes 
(b)  
1. Dilute sulphuric acid treated with zinc gives Hydrogen gas which bums with pop sound. 
Concentrated H2SO4 gives SO2 gas with zinc and the gas turns Acidified potassium 
dichromate paper green. 
2. Barium chloride solution gives white ppt. with dilute H2SO4, This white ppt. is insoluble 
in all acids. 
Concentrated H2SO4 and NaCl mixture when heated gives dense white fumes if glass rod 
dipped in Ammonia solution is brought near it. 
 
 
Question 7:  
Name the products formed when hot and concentrated sulphuric acid reacts with the following: 
(a) Sulphur         (b) NaOH,     
(c) Sugar            (d) Carbon     
(e) Copper. 
Page 4


Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
Top tutor. 
 
Question 1:  
Comment, sulphuric acid is referred to as: 
(a) King of chemicals                                    (b) Oil of vitriol 
Solution 1: 
(a) Sulphuric acid is called King of Chemicals because there is no other manufactured  
       compound which is used by such a large number of key industries. 
(b) Sulphuric acid is referred to as Oil of vitriol as it was obtained as an oily viscous liquid by  
      heating crystals of green vitriol. 
 
 
Question 2:  
Sulphuric acid is manufactured by contact process 
(a) Give two balanced equations to obtain SO2 in this process. 
(b) Give the conditions for the oxidation of SO2 
Solution 2: 
(a) Two balanced equations to obtain SO2 is: 
(i) 
2 2 2 3 2
4FeS + 11O  2Fe O + 8SO ?  
(ii) S + O2 ? SO2 
(b) The conditions for the oxidation of SO2 are: 
(i) The temperature should be as low as possible. The yield has been found to be maximum 
at about 410
0
C - 450
o
C 
(ii) High pressure (2 atm) is favoured because the product formed has less volume than 
reactant. 
(iii) Excess of oxygen increases the production of sulphur trioxide. 
(iv) Vanadium pentoxide or platinised asbestos is used as catalyst. 
(c) Sulphuric acid is not obtained directly by reacting SO3 with water because the reaction is 
highly exothermic which produce the fine misty droplets of sulphuric acid that is not directly 
absorbed by water. 
(d) The chemical used to dissolve SO3 is concentrated sulphuric acid. The product formed is 
oleum. 
(e) Main reactions of this process are: 
22
S O SO ?? 
2S
VO
2 2 3
450 C
2SO O 2SO ? 
3 2 4 2 2 7
2 2 7 2 2 4
SO H SO H S O
H S O H O 2H SO
??
??
 
 
 
Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
 
Top tutor. 
Question 3:  
Why is water not added to concentrated H2SO4 in order to dilute it? 
Solution 3: 
Water is not added to concentrated acid since it is an exothermic reaction. If water is added to 
the acid, there is a sudden increase in temperature and the acid being in bulk tends to spurt out 
with serious consequences. 
 
 
Question 4:  
Why the impurity of arsenic oxide must be removed before passing the mixture of SO4 and air 
through the catalytic chamber? 
Solution 4: 
Impurity of ARSENIC poisons the catalyst [i.e. deactivates the catalyst]. So, it must be removed 
before passing the mixture of SO2 air through the catalytic chamber. 
 
 
Question 5:  
Give two balanced reactions of each type to show the following properties of sulphuric acid: 
(a) Acidic nature.              (b) Oxidising agent, 
(c) Hygroscopic nature,     (d) Non-volatile nature 
Solution 5: 
Balanced reactions are: 
(a) (a) Acidic nature: 
(i) Dilute H2SO4 reacts with basic oxides to form sulphate and water. 
     2 NaOH + H2SO4 ?Na2SO4 + 2H2O 
(ii) CuO + H2SO4 ? CuSO4 + H2O 
(iii) It reacts with carbonate to produce CO2. 
       Na2CO3 + H2SO4 ?Na2SO4 + H2O + CO2 ? 
(b) Oxidising agent: 
H2SO4 ?H2O +SO2 + [O] 
Nascent oxygen oxidizes non-metals, metals and inorganic compounds. 
For example, 
Carbon to carbon dioxide 
C+H2SO4 ? CO2 +H2O +2SO2 
Sulphur to sulphur dioxide 
S +H2SO4 ? 3SO2 +2H2O 
Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
 
Top tutor. 
(c) Hygroscopic nature: 
       It has great affinity for water. It readily absorbs moisture from atmospheric air. 
HCOOH 
24
conc.H SO
? ? ? ? ?CO + H2O 
C6H12O6 
24
conc.H SO
? ? ? ? ? 6C + 6H2O 
(d) Non-volatile nature: 
It has a high boiling point (356
o
C) so it is considered to be non-volatile. Therefore, it is used 
for preparing volatile acids like hydrochloric acid, nitric acid from their salts by double 
decomposition reaction. 
NaCl + H2SO4 ?NaHSO4 + HCl 
KCl + H2SO4 ? KHSO4 + HCl 
 
 
Question 6:  
Give a chemical test to distinguish between: 
(a) dilute sulphuric acid and dilute hydrochloric acid 
(b) dilute sulphuric acid and conc. Sulphuric acid 
Solution 6: 
(a) Bring a glass rod dipped in Ammonia solution near the mouth of each test tubes containing 
dil. Hel and dil. H2SO4each. 
Dil HCl Dil. H2SO4 
White fumes of ammonium 
chloride 
No such fumes 
(b)  
1. Dilute sulphuric acid treated with zinc gives Hydrogen gas which bums with pop sound. 
Concentrated H2SO4 gives SO2 gas with zinc and the gas turns Acidified potassium 
dichromate paper green. 
2. Barium chloride solution gives white ppt. with dilute H2SO4, This white ppt. is insoluble 
in all acids. 
Concentrated H2SO4 and NaCl mixture when heated gives dense white fumes if glass rod 
dipped in Ammonia solution is brought near it. 
 
 
Question 7:  
Name the products formed when hot and concentrated sulphuric acid reacts with the following: 
(a) Sulphur         (b) NaOH,     
(c) Sugar            (d) Carbon     
(e) Copper. 
Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
 
Top tutor. 
Solution 7: 
(a) When sulphuric acid reacts with sulphur the product formed is Sulphur dioxide is formed. 
       S +2H2SO4 ? 3SO2 + 2H2O 
(b) When sulphuric acid reacts with sodium hydroxide it neutralizes base to form sodium 
sulphate. 
      2NaOH + H2SO4 ? Na2SO4 + 2H2O 
(c) When sulphuric acid reacts with sugar it forms carbon 
       C12 H22O11 
24
conc.H SO
? ? ? ? ?12C + 11H2O 
(d) When sulphuric acid reacts with carbon it forms carbon dioxide and sulphur dioxide gas. 
      C + 2H2SO4 ? CO2 + 2H2O + 2SO2 ?
 
(e) When sulphuric acid reacts with copper it forms copper sulphate and sulphur dioxide. 
       Cu + H2SO4 ? CuSO4 + 2H2O + SO2 ? 
 
 
Question 8:  
Why is: 
(a) Concentrated sulphuric acid kept in air tight bottles? 
(b) H2SO4 not a drying agent for H2S? 
(c) Sulphuric acid used in the preparation of HCI and HNO3? Give equations in both cases. 
Solution 8: 
(a) Concentrated sulphuric acid is hygroscopic substance that absorbs moisture when exposed 
to air. Hence, it is stored in air tight bottles. 
(b) Sulphuric acid is not a drying agent for H2S because it reacts with H2S to form sulphur. 
      H2SO4 + H2S ?2H2O + SO2 + S ? 
(c) Concentrated sulphuric acid has high boiling point (356
o
C). So, it is considered to be non-
volatile. Hence, it is used for preparing volatile acids like Hydrochloric acid and Nitric acids 
from their salts by double decomposition. 
NaCl + H2SO4 ?NaHSO4 + HCl 
NaNO3 + H2SO4 ?NaHSO4 + HNO3 
 
 
Question 9:  
What property of conc. H2SO4 is made use of in each of in each of the following cases? Give an 
equation for the reaction on each case: 
(a) in the production of HCI gas when it reacts with a chloride, 
(b) in the preparation of CO and HCOOH, 
Page 5


Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
Top tutor. 
 
Question 1:  
Comment, sulphuric acid is referred to as: 
(a) King of chemicals                                    (b) Oil of vitriol 
Solution 1: 
(a) Sulphuric acid is called King of Chemicals because there is no other manufactured  
       compound which is used by such a large number of key industries. 
(b) Sulphuric acid is referred to as Oil of vitriol as it was obtained as an oily viscous liquid by  
      heating crystals of green vitriol. 
 
 
Question 2:  
Sulphuric acid is manufactured by contact process 
(a) Give two balanced equations to obtain SO2 in this process. 
(b) Give the conditions for the oxidation of SO2 
Solution 2: 
(a) Two balanced equations to obtain SO2 is: 
(i) 
2 2 2 3 2
4FeS + 11O  2Fe O + 8SO ?  
(ii) S + O2 ? SO2 
(b) The conditions for the oxidation of SO2 are: 
(i) The temperature should be as low as possible. The yield has been found to be maximum 
at about 410
0
C - 450
o
C 
(ii) High pressure (2 atm) is favoured because the product formed has less volume than 
reactant. 
(iii) Excess of oxygen increases the production of sulphur trioxide. 
(iv) Vanadium pentoxide or platinised asbestos is used as catalyst. 
(c) Sulphuric acid is not obtained directly by reacting SO3 with water because the reaction is 
highly exothermic which produce the fine misty droplets of sulphuric acid that is not directly 
absorbed by water. 
(d) The chemical used to dissolve SO3 is concentrated sulphuric acid. The product formed is 
oleum. 
(e) Main reactions of this process are: 
22
S O SO ?? 
2S
VO
2 2 3
450 C
2SO O 2SO ? 
3 2 4 2 2 7
2 2 7 2 2 4
SO H SO H S O
H S O H O 2H SO
??
??
 
 
 
Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
 
Top tutor. 
Question 3:  
Why is water not added to concentrated H2SO4 in order to dilute it? 
Solution 3: 
Water is not added to concentrated acid since it is an exothermic reaction. If water is added to 
the acid, there is a sudden increase in temperature and the acid being in bulk tends to spurt out 
with serious consequences. 
 
 
Question 4:  
Why the impurity of arsenic oxide must be removed before passing the mixture of SO4 and air 
through the catalytic chamber? 
Solution 4: 
Impurity of ARSENIC poisons the catalyst [i.e. deactivates the catalyst]. So, it must be removed 
before passing the mixture of SO2 air through the catalytic chamber. 
 
 
Question 5:  
Give two balanced reactions of each type to show the following properties of sulphuric acid: 
(a) Acidic nature.              (b) Oxidising agent, 
(c) Hygroscopic nature,     (d) Non-volatile nature 
Solution 5: 
Balanced reactions are: 
(a) (a) Acidic nature: 
(i) Dilute H2SO4 reacts with basic oxides to form sulphate and water. 
     2 NaOH + H2SO4 ?Na2SO4 + 2H2O 
(ii) CuO + H2SO4 ? CuSO4 + H2O 
(iii) It reacts with carbonate to produce CO2. 
       Na2CO3 + H2SO4 ?Na2SO4 + H2O + CO2 ? 
(b) Oxidising agent: 
H2SO4 ?H2O +SO2 + [O] 
Nascent oxygen oxidizes non-metals, metals and inorganic compounds. 
For example, 
Carbon to carbon dioxide 
C+H2SO4 ? CO2 +H2O +2SO2 
Sulphur to sulphur dioxide 
S +H2SO4 ? 3SO2 +2H2O 
Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
 
Top tutor. 
(c) Hygroscopic nature: 
       It has great affinity for water. It readily absorbs moisture from atmospheric air. 
HCOOH 
24
conc.H SO
? ? ? ? ?CO + H2O 
C6H12O6 
24
conc.H SO
? ? ? ? ? 6C + 6H2O 
(d) Non-volatile nature: 
It has a high boiling point (356
o
C) so it is considered to be non-volatile. Therefore, it is used 
for preparing volatile acids like hydrochloric acid, nitric acid from their salts by double 
decomposition reaction. 
NaCl + H2SO4 ?NaHSO4 + HCl 
KCl + H2SO4 ? KHSO4 + HCl 
 
 
Question 6:  
Give a chemical test to distinguish between: 
(a) dilute sulphuric acid and dilute hydrochloric acid 
(b) dilute sulphuric acid and conc. Sulphuric acid 
Solution 6: 
(a) Bring a glass rod dipped in Ammonia solution near the mouth of each test tubes containing 
dil. Hel and dil. H2SO4each. 
Dil HCl Dil. H2SO4 
White fumes of ammonium 
chloride 
No such fumes 
(b)  
1. Dilute sulphuric acid treated with zinc gives Hydrogen gas which bums with pop sound. 
Concentrated H2SO4 gives SO2 gas with zinc and the gas turns Acidified potassium 
dichromate paper green. 
2. Barium chloride solution gives white ppt. with dilute H2SO4, This white ppt. is insoluble 
in all acids. 
Concentrated H2SO4 and NaCl mixture when heated gives dense white fumes if glass rod 
dipped in Ammonia solution is brought near it. 
 
 
Question 7:  
Name the products formed when hot and concentrated sulphuric acid reacts with the following: 
(a) Sulphur         (b) NaOH,     
(c) Sugar            (d) Carbon     
(e) Copper. 
Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
 
Top tutor. 
Solution 7: 
(a) When sulphuric acid reacts with sulphur the product formed is Sulphur dioxide is formed. 
       S +2H2SO4 ? 3SO2 + 2H2O 
(b) When sulphuric acid reacts with sodium hydroxide it neutralizes base to form sodium 
sulphate. 
      2NaOH + H2SO4 ? Na2SO4 + 2H2O 
(c) When sulphuric acid reacts with sugar it forms carbon 
       C12 H22O11 
24
conc.H SO
? ? ? ? ?12C + 11H2O 
(d) When sulphuric acid reacts with carbon it forms carbon dioxide and sulphur dioxide gas. 
      C + 2H2SO4 ? CO2 + 2H2O + 2SO2 ?
 
(e) When sulphuric acid reacts with copper it forms copper sulphate and sulphur dioxide. 
       Cu + H2SO4 ? CuSO4 + 2H2O + SO2 ? 
 
 
Question 8:  
Why is: 
(a) Concentrated sulphuric acid kept in air tight bottles? 
(b) H2SO4 not a drying agent for H2S? 
(c) Sulphuric acid used in the preparation of HCI and HNO3? Give equations in both cases. 
Solution 8: 
(a) Concentrated sulphuric acid is hygroscopic substance that absorbs moisture when exposed 
to air. Hence, it is stored in air tight bottles. 
(b) Sulphuric acid is not a drying agent for H2S because it reacts with H2S to form sulphur. 
      H2SO4 + H2S ?2H2O + SO2 + S ? 
(c) Concentrated sulphuric acid has high boiling point (356
o
C). So, it is considered to be non-
volatile. Hence, it is used for preparing volatile acids like Hydrochloric acid and Nitric acids 
from their salts by double decomposition. 
NaCl + H2SO4 ?NaHSO4 + HCl 
NaNO3 + H2SO4 ?NaHSO4 + HNO3 
 
 
Question 9:  
What property of conc. H2SO4 is made use of in each of in each of the following cases? Give an 
equation for the reaction on each case: 
(a) in the production of HCI gas when it reacts with a chloride, 
(b) in the preparation of CO and HCOOH, 
Class X Chapter 11 – Sulphuric Acid Chemistry 
______________________________________________________________________________ 
 
Top tutor. 
(c) as a source of hydrogen by diluting it and adding a strip of magnesium. 
(d) in the preparation of sulphur dioxide by warming a mixture of conc. Sulphuric acid and  
      copper – turnings, 
(e) Hydrogen sulphide gas is passed through concentrated sulphuric acid. 
Solution 9: 
(a) Due to its reducing property. i.e, it is a non-volatile acid. 
NaCl + H2SO4 ?NaHSO4 + HCl 
(Conc.) 
(b) It is a dehydrating agent. 
        HCOOH 
24
conc.H SO
? ? ? ? ?CO + H2O 
(c) Magnesium is present above hydrogen in the reactivity series so sulphuric acid is able to 
liberate hydrogen gas by reacting with magnesium strip. 
        Mg + H2SO4 ? MgSO4 + H2 
(d) Due to its oxidizing character 
        Cu + H2SO4 ? CuSO4 + 2H2O + SO2 
(e) Due to its oxidizing property Hydrogen sulphide gas is passed through concentrated 
sulphuric acid to liberate sulphur dioxide and sulphur is formed. 
        H2S + H2SO4 ? S + 2H2O + SO2 
 
 
Question 10:  
What is the name given to the salts of: 
(a) sulphurous acid          (b) sulphuric acid? 
Solution 10: 
The name of the salt of 
(a) Hydrogen sulphites and Sulphites. 
(b) Sulphate and bisulphate. 
 
 
Question 11:  
Give reasons for the following: 
(a) Sulphuric acid forms two types of salts with NaOH, 
(b) Red brown vapours are produced when concentrated sulphuric acid is added to hydrogen  
      bromide. 
(c) A piece of wood becomes black when concentrated sulphuric acid is poured on it, 
(d) Brisk effervescence is seen when oil of vitriol is added to sodium carbonate.