Selina Textbook Solutions: Study of Compounds - Hydrogen Chloride | Chemistry Class 10 ICSE PDF Download

 Page 1


Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
EXERCISE 
 
Question 1:  
Draw a labelled diagram for the laboratory preparation of hydrogen chloride gas. Give the 
balanced equation for the reaction. 
Solution 1: 
Labelled Diagram for laboratory preparation of Hydrogen chloride is: 
 
Balanced equation: NaCl +H2SO4   
<200°C  
    NaHSO4 + HCl ? 
 
 
Question 2: 
Name the drying agents: 
(a) used in drying hydrogen chloride gas. 
(b) phosphorus pentoxide and calcium oxide are good drying agent but they cannot be used to 
dry hydrogen chloride gas. Why? 
Solution 2: 
(a) Hydrogen chloride is dried by passing through conc. Sulphuric acid. 
(b) Phosphorous pentoxide and CaO cannot be used to dry HCl because they react   with HCl. 
     2P2O5+ 3HCl ? POCl3 + 3HPO3 
     CaO + 2HCl ? CaCl2 + H2O 
 
 
 
 
 
Page 2


Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
EXERCISE 
 
Question 1:  
Draw a labelled diagram for the laboratory preparation of hydrogen chloride gas. Give the 
balanced equation for the reaction. 
Solution 1: 
Labelled Diagram for laboratory preparation of Hydrogen chloride is: 
 
Balanced equation: NaCl +H2SO4   
<200°C  
    NaHSO4 + HCl ? 
 
 
Question 2: 
Name the drying agents: 
(a) used in drying hydrogen chloride gas. 
(b) phosphorus pentoxide and calcium oxide are good drying agent but they cannot be used to 
dry hydrogen chloride gas. Why? 
Solution 2: 
(a) Hydrogen chloride is dried by passing through conc. Sulphuric acid. 
(b) Phosphorous pentoxide and CaO cannot be used to dry HCl because they react   with HCl. 
     2P2O5+ 3HCl ? POCl3 + 3HPO3 
     CaO + 2HCl ? CaCl2 + H2O 
 
 
 
 
 
Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
Question 3: 
Explain why: 
(a) Anhydrous HCl is poor conductor while aqueous HCl is excellent conductor. 
(b) When the stopper of a bottle full of hydrogen chloride gas is opened there are fumes in the 
air. 
(c) A solution of hydrogen chloride in water turns blue litmus red, and conducts electricity, 
while a solution of the same gas in toluene: 
(i) has no effect on litmus, and 
(ii) does not conduct electricity. 
(d) thick white fumes are formed when a glass rod dipped in NH2OH is brought near the mouth 
of a bottle full of HCl gas. 
(e) dry hydrogen chloride gas does not affect a dry strip of blue litmus paper but it turns red in 
the presence of a drop of water. 
(f) hydrogen chloride gas is not collected over water. 
Solution 3: 
(a) Anhydrous HCl is poor conductor due to the absence of ions in it whereas aqueous HCl is 
excellent conductor since it contains ions. 
(b) When the stopper is opened HCl gas comes in contact with water vapors of air and gives 
white fumes due to the formation of hydrochloric acid. 
(c) A solution of HCl in water gives hydronium ions and conducts electricity, but HCl is also 
soluble in dry toluene, but in that case it neither (i) turns blue litmus red (ii) nor does 
conducts electricity. This indicates the absence of H
+
 ions in toluene showing thereby that 
hydrogen chloride is a covalent compound. 
(d) When ammonium hydroxide is brought near the mouth of HCl, dense white fumes are 
formed due to the formation of ammonium chloride. 
        HCl + NH4OH ? NH4Cl + H2O 
(e) Dry hydrogen chloride is not acidic whereas moist Hydrogen chloride is acidic. In presence 
of a drop of water HCl gas dissolves in water and forms hydrochloric acid which turns blue 
litmus paper red. 
(f) Hydrogen chloride is not collected over water as it is highly soluble in water. 
 
 
 
 
 
 
 
 
Page 3


Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
EXERCISE 
 
Question 1:  
Draw a labelled diagram for the laboratory preparation of hydrogen chloride gas. Give the 
balanced equation for the reaction. 
Solution 1: 
Labelled Diagram for laboratory preparation of Hydrogen chloride is: 
 
Balanced equation: NaCl +H2SO4   
<200°C  
    NaHSO4 + HCl ? 
 
 
Question 2: 
Name the drying agents: 
(a) used in drying hydrogen chloride gas. 
(b) phosphorus pentoxide and calcium oxide are good drying agent but they cannot be used to 
dry hydrogen chloride gas. Why? 
Solution 2: 
(a) Hydrogen chloride is dried by passing through conc. Sulphuric acid. 
(b) Phosphorous pentoxide and CaO cannot be used to dry HCl because they react   with HCl. 
     2P2O5+ 3HCl ? POCl3 + 3HPO3 
     CaO + 2HCl ? CaCl2 + H2O 
 
 
 
 
 
Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
Question 3: 
Explain why: 
(a) Anhydrous HCl is poor conductor while aqueous HCl is excellent conductor. 
(b) When the stopper of a bottle full of hydrogen chloride gas is opened there are fumes in the 
air. 
(c) A solution of hydrogen chloride in water turns blue litmus red, and conducts electricity, 
while a solution of the same gas in toluene: 
(i) has no effect on litmus, and 
(ii) does not conduct electricity. 
(d) thick white fumes are formed when a glass rod dipped in NH2OH is brought near the mouth 
of a bottle full of HCl gas. 
(e) dry hydrogen chloride gas does not affect a dry strip of blue litmus paper but it turns red in 
the presence of a drop of water. 
(f) hydrogen chloride gas is not collected over water. 
Solution 3: 
(a) Anhydrous HCl is poor conductor due to the absence of ions in it whereas aqueous HCl is 
excellent conductor since it contains ions. 
(b) When the stopper is opened HCl gas comes in contact with water vapors of air and gives 
white fumes due to the formation of hydrochloric acid. 
(c) A solution of HCl in water gives hydronium ions and conducts electricity, but HCl is also 
soluble in dry toluene, but in that case it neither (i) turns blue litmus red (ii) nor does 
conducts electricity. This indicates the absence of H
+
 ions in toluene showing thereby that 
hydrogen chloride is a covalent compound. 
(d) When ammonium hydroxide is brought near the mouth of HCl, dense white fumes are 
formed due to the formation of ammonium chloride. 
        HCl + NH4OH ? NH4Cl + H2O 
(e) Dry hydrogen chloride is not acidic whereas moist Hydrogen chloride is acidic. In presence 
of a drop of water HCl gas dissolves in water and forms hydrochloric acid which turns blue 
litmus paper red. 
(f) Hydrogen chloride is not collected over water as it is highly soluble in water. 
 
 
 
 
 
 
 
 
Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
Question 4: 
Write the main difference in hydrogen chloride gas and hydrochloric acid. 
Solution 4: 
Difference between Hydrogen chloride gas and Hydrochloric acid is: 
Hydrogen chloride gas Hydrochloric acid 
1. Dry hydrogen chloride gas does not 
turn blue litmus red due to non-
acidic character. 
2. Hydrogen chloride gas does not 
conduct electricity. 
1. Being acidic it turns blue litmus red. 
2. Hydrochloric acid is a good 
conductor of electricity. 
 
 
 
Question 5: 
The given set up in the figure is for the preparation of an acid. 
(a) Name the acid prepared by this method. 
 
(b) name the reactants used. 
(c) why empty flask is used 
(d) what is the drying agent used? Why is this drying agent chosen? 
(e) what is the role of inverted funnel in the arrangement 
Solution 5:  
Hydrochloric acid is prepared by this method. 
(a) The reactants are sodium chloride and Sulphuric acid. 
(b) The empty flask acts as Anti-Suction device. In case the back suction occurs the water will 
collect in it and will not reach the generating flask. 
(c) The drying agent is Conc. Sulphuric acid. Sulphuric acid is chosen as drying agent because 
it does not react with HCl. 
(d) The Inverted funnel : 
Prevents or minimizes back suction of water. 
Provides a large surface area for absorption of HCl gas. 
 
 
Page 4


Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
EXERCISE 
 
Question 1:  
Draw a labelled diagram for the laboratory preparation of hydrogen chloride gas. Give the 
balanced equation for the reaction. 
Solution 1: 
Labelled Diagram for laboratory preparation of Hydrogen chloride is: 
 
Balanced equation: NaCl +H2SO4   
<200°C  
    NaHSO4 + HCl ? 
 
 
Question 2: 
Name the drying agents: 
(a) used in drying hydrogen chloride gas. 
(b) phosphorus pentoxide and calcium oxide are good drying agent but they cannot be used to 
dry hydrogen chloride gas. Why? 
Solution 2: 
(a) Hydrogen chloride is dried by passing through conc. Sulphuric acid. 
(b) Phosphorous pentoxide and CaO cannot be used to dry HCl because they react   with HCl. 
     2P2O5+ 3HCl ? POCl3 + 3HPO3 
     CaO + 2HCl ? CaCl2 + H2O 
 
 
 
 
 
Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
Question 3: 
Explain why: 
(a) Anhydrous HCl is poor conductor while aqueous HCl is excellent conductor. 
(b) When the stopper of a bottle full of hydrogen chloride gas is opened there are fumes in the 
air. 
(c) A solution of hydrogen chloride in water turns blue litmus red, and conducts electricity, 
while a solution of the same gas in toluene: 
(i) has no effect on litmus, and 
(ii) does not conduct electricity. 
(d) thick white fumes are formed when a glass rod dipped in NH2OH is brought near the mouth 
of a bottle full of HCl gas. 
(e) dry hydrogen chloride gas does not affect a dry strip of blue litmus paper but it turns red in 
the presence of a drop of water. 
(f) hydrogen chloride gas is not collected over water. 
Solution 3: 
(a) Anhydrous HCl is poor conductor due to the absence of ions in it whereas aqueous HCl is 
excellent conductor since it contains ions. 
(b) When the stopper is opened HCl gas comes in contact with water vapors of air and gives 
white fumes due to the formation of hydrochloric acid. 
(c) A solution of HCl in water gives hydronium ions and conducts electricity, but HCl is also 
soluble in dry toluene, but in that case it neither (i) turns blue litmus red (ii) nor does 
conducts electricity. This indicates the absence of H
+
 ions in toluene showing thereby that 
hydrogen chloride is a covalent compound. 
(d) When ammonium hydroxide is brought near the mouth of HCl, dense white fumes are 
formed due to the formation of ammonium chloride. 
        HCl + NH4OH ? NH4Cl + H2O 
(e) Dry hydrogen chloride is not acidic whereas moist Hydrogen chloride is acidic. In presence 
of a drop of water HCl gas dissolves in water and forms hydrochloric acid which turns blue 
litmus paper red. 
(f) Hydrogen chloride is not collected over water as it is highly soluble in water. 
 
 
 
 
 
 
 
 
Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
Question 4: 
Write the main difference in hydrogen chloride gas and hydrochloric acid. 
Solution 4: 
Difference between Hydrogen chloride gas and Hydrochloric acid is: 
Hydrogen chloride gas Hydrochloric acid 
1. Dry hydrogen chloride gas does not 
turn blue litmus red due to non-
acidic character. 
2. Hydrogen chloride gas does not 
conduct electricity. 
1. Being acidic it turns blue litmus red. 
2. Hydrochloric acid is a good 
conductor of electricity. 
 
 
 
Question 5: 
The given set up in the figure is for the preparation of an acid. 
(a) Name the acid prepared by this method. 
 
(b) name the reactants used. 
(c) why empty flask is used 
(d) what is the drying agent used? Why is this drying agent chosen? 
(e) what is the role of inverted funnel in the arrangement 
Solution 5:  
Hydrochloric acid is prepared by this method. 
(a) The reactants are sodium chloride and Sulphuric acid. 
(b) The empty flask acts as Anti-Suction device. In case the back suction occurs the water will 
collect in it and will not reach the generating flask. 
(c) The drying agent is Conc. Sulphuric acid. Sulphuric acid is chosen as drying agent because 
it does not react with HCl. 
(d) The Inverted funnel : 
Prevents or minimizes back suction of water. 
Provides a large surface area for absorption of HCl gas. 
 
 
Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
Question 6: 
Write an equation for the reactions of aqueous hydrochloric acid on: 
(a) silver nitrate solution                  (b) magnesium foil 
(c) caustic soda solution                   (d) zinc carbonate 
(e) lead nitrate solution                     (f) copper oxide 
Solution 6: 
Equations are: 
(a) AgNO3 + HCl ? AgCl + HNO3 
(b) Mg + 2HCl ? MgCl2 + H2 
(c) NaOH + HCl ? NaCl + H2O 
(d) ZnCO3 +2HCl ? ZnCl2 + H2O +CO2 
(e) Pb(NO3)2 + 2HCl ? PbCl2 + 2HNO3 
(f) CuO + 2HCl ? CuCl2 + H2O 
 
 
Question 7: 
(a) Name an element which reacts with hydrogen to form a compound which is strongly acidic 
in water. 
(b) Explain why dilute hydrochloric acid cannot be concentrated by boiling beyond 22.2%. 
Solution 7: 
(c) Chlorine. 
       The compound formed which is strongly acidic in water, is HCl. 
        H2 + Cl2 ? 2HCl 
(d) A dilute aqueous solution of hydrochloric acid gets gradually concentrated on distillation, 
till the concentration of the acid reaches 22.2% HCl by weight which boils at 110
0
C. When 
this concentration is reached, no further increase in concentration of the acid becomes 
possible by boiling. This is because vapours evolved before 110
0
C are vapours of water but 
at temperature above 110
0
C vapours consist mostly of molecules of HCl. 
 
 
Question 8: 
Hydrochloric acid contains (i) hydrogen (ii) chlorine. Prove it. Write equations for the reactions. 
Solution 8: 
We can prove that hydrochloric acid contains both hydrogen and chlorine by the following 
experiment. 
Take a voltameter used for electrolysis of water, fitted with platinum cathode and graphite anode. 
Into the voltameter pour 4 molar HCl and pass direct current. 
Page 5


Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
EXERCISE 
 
Question 1:  
Draw a labelled diagram for the laboratory preparation of hydrogen chloride gas. Give the 
balanced equation for the reaction. 
Solution 1: 
Labelled Diagram for laboratory preparation of Hydrogen chloride is: 
 
Balanced equation: NaCl +H2SO4   
<200°C  
    NaHSO4 + HCl ? 
 
 
Question 2: 
Name the drying agents: 
(a) used in drying hydrogen chloride gas. 
(b) phosphorus pentoxide and calcium oxide are good drying agent but they cannot be used to 
dry hydrogen chloride gas. Why? 
Solution 2: 
(a) Hydrogen chloride is dried by passing through conc. Sulphuric acid. 
(b) Phosphorous pentoxide and CaO cannot be used to dry HCl because they react   with HCl. 
     2P2O5+ 3HCl ? POCl3 + 3HPO3 
     CaO + 2HCl ? CaCl2 + H2O 
 
 
 
 
 
Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
Question 3: 
Explain why: 
(a) Anhydrous HCl is poor conductor while aqueous HCl is excellent conductor. 
(b) When the stopper of a bottle full of hydrogen chloride gas is opened there are fumes in the 
air. 
(c) A solution of hydrogen chloride in water turns blue litmus red, and conducts electricity, 
while a solution of the same gas in toluene: 
(i) has no effect on litmus, and 
(ii) does not conduct electricity. 
(d) thick white fumes are formed when a glass rod dipped in NH2OH is brought near the mouth 
of a bottle full of HCl gas. 
(e) dry hydrogen chloride gas does not affect a dry strip of blue litmus paper but it turns red in 
the presence of a drop of water. 
(f) hydrogen chloride gas is not collected over water. 
Solution 3: 
(a) Anhydrous HCl is poor conductor due to the absence of ions in it whereas aqueous HCl is 
excellent conductor since it contains ions. 
(b) When the stopper is opened HCl gas comes in contact with water vapors of air and gives 
white fumes due to the formation of hydrochloric acid. 
(c) A solution of HCl in water gives hydronium ions and conducts electricity, but HCl is also 
soluble in dry toluene, but in that case it neither (i) turns blue litmus red (ii) nor does 
conducts electricity. This indicates the absence of H
+
 ions in toluene showing thereby that 
hydrogen chloride is a covalent compound. 
(d) When ammonium hydroxide is brought near the mouth of HCl, dense white fumes are 
formed due to the formation of ammonium chloride. 
        HCl + NH4OH ? NH4Cl + H2O 
(e) Dry hydrogen chloride is not acidic whereas moist Hydrogen chloride is acidic. In presence 
of a drop of water HCl gas dissolves in water and forms hydrochloric acid which turns blue 
litmus paper red. 
(f) Hydrogen chloride is not collected over water as it is highly soluble in water. 
 
 
 
 
 
 
 
 
Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
Question 4: 
Write the main difference in hydrogen chloride gas and hydrochloric acid. 
Solution 4: 
Difference between Hydrogen chloride gas and Hydrochloric acid is: 
Hydrogen chloride gas Hydrochloric acid 
1. Dry hydrogen chloride gas does not 
turn blue litmus red due to non-
acidic character. 
2. Hydrogen chloride gas does not 
conduct electricity. 
1. Being acidic it turns blue litmus red. 
2. Hydrochloric acid is a good 
conductor of electricity. 
 
 
 
Question 5: 
The given set up in the figure is for the preparation of an acid. 
(a) Name the acid prepared by this method. 
 
(b) name the reactants used. 
(c) why empty flask is used 
(d) what is the drying agent used? Why is this drying agent chosen? 
(e) what is the role of inverted funnel in the arrangement 
Solution 5:  
Hydrochloric acid is prepared by this method. 
(a) The reactants are sodium chloride and Sulphuric acid. 
(b) The empty flask acts as Anti-Suction device. In case the back suction occurs the water will 
collect in it and will not reach the generating flask. 
(c) The drying agent is Conc. Sulphuric acid. Sulphuric acid is chosen as drying agent because 
it does not react with HCl. 
(d) The Inverted funnel : 
Prevents or minimizes back suction of water. 
Provides a large surface area for absorption of HCl gas. 
 
 
Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
Question 6: 
Write an equation for the reactions of aqueous hydrochloric acid on: 
(a) silver nitrate solution                  (b) magnesium foil 
(c) caustic soda solution                   (d) zinc carbonate 
(e) lead nitrate solution                     (f) copper oxide 
Solution 6: 
Equations are: 
(a) AgNO3 + HCl ? AgCl + HNO3 
(b) Mg + 2HCl ? MgCl2 + H2 
(c) NaOH + HCl ? NaCl + H2O 
(d) ZnCO3 +2HCl ? ZnCl2 + H2O +CO2 
(e) Pb(NO3)2 + 2HCl ? PbCl2 + 2HNO3 
(f) CuO + 2HCl ? CuCl2 + H2O 
 
 
Question 7: 
(a) Name an element which reacts with hydrogen to form a compound which is strongly acidic 
in water. 
(b) Explain why dilute hydrochloric acid cannot be concentrated by boiling beyond 22.2%. 
Solution 7: 
(c) Chlorine. 
       The compound formed which is strongly acidic in water, is HCl. 
        H2 + Cl2 ? 2HCl 
(d) A dilute aqueous solution of hydrochloric acid gets gradually concentrated on distillation, 
till the concentration of the acid reaches 22.2% HCl by weight which boils at 110
0
C. When 
this concentration is reached, no further increase in concentration of the acid becomes 
possible by boiling. This is because vapours evolved before 110
0
C are vapours of water but 
at temperature above 110
0
C vapours consist mostly of molecules of HCl. 
 
 
Question 8: 
Hydrochloric acid contains (i) hydrogen (ii) chlorine. Prove it. Write equations for the reactions. 
Solution 8: 
We can prove that hydrochloric acid contains both hydrogen and chlorine by the following 
experiment. 
Take a voltameter used for electrolysis of water, fitted with platinum cathode and graphite anode. 
Into the voltameter pour 4 molar HCl and pass direct current. 
Class X Chapter-8 – Hydrogen Chloride  Chemistry  
______________________________________________________________________________ 
 
It is seen that a colourless gas is evolved at cathode and a greenish gas is evolved at anode. 
When a burning splinter is brought near a colourless gas, it bursts into flame thereby proving 
that it is hydrogen gas. 
When moist starch iodide paper is held in the greenish yellow gas, it turns blue black, thereby 
proving that the gas is chlorine. 
2HCl ? H2 + Cl2 
This experiment proves that hydrochloric acid contains both hydrogen and chlorine. 
 
 
Question 9: 
Name: 
(a) black metallic oxide which reacts with hydrochloric acid to give a coloured solution. 
(b) two colourless gases, which when mixed produce a white solid. 
(c) two gases which chemically combine to form a liquid 
(d) a chloride which is solube in excess of ammonium hydroxide  
(e) the chemical in which gold can be dissolved 
(f) the experiment which demonstrates that hydrogen chloride is soluble in water. 
(g) the gas produced when chlorine water is exposed to sunlight 
Solution 9: 
(a) Manganese dioxide 
(b) Hydrogen chloride and ammonia 
(c) Hydrogen and oxygen 
(d) AgCl(Silver chloride) 
(e) Aqua regia 
(f) Fountain experiment 
(g) Hydrogen chloride gas 
 
 
Question 10: 
Give reasons for the following: 
(a) An aqueous solution of chlorine in acidic in nature  
Hint : Cl2 + H2O ? HCl +HClO 
(b) silver nitrate solution can be used to distinguish HCl from HNO3 
Solution 10: 
(a) An aqueous solution of chlorine is acidic as it dissolves in water to form hydrochloric and 
hypochlorous acids.