ICSE Solutions for Chapter 8 Hydrogen Chloride Class 10 Selina Chemistry
Exercise 8 A
(a) Anhydrous HCl is a poor conductor while aqueous HCl is an 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 1: (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.
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
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.
Question 2: Write the main difference in hydrogen chloride gas and hydrochloric acid.
Solution 2: Difference between Hydrogen chloride gas and Hydrochloric acid is:
Question 3: 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 the inverted funnel in the arrangement
Solution 3: 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 a 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.
Question 4: 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 4: 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 5: (a) Name an element which reacts with hydrogen to form a compound which is strongly acidic in water.
(b) Explain why to dilute hydrochloric acid cannot be concentrated by boiling beyond 22.2%.
Solution 5: (a) Chlorine.
The compound formed which is strongly acidic in water is HCl.
H2 + Cl2 → 2HCl
Question 2: Write the main difference in hydrogen chloride gas and hydrochloric acid.
Solution 2: 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. |
1. Being acidic, it turns blue litmus red. |
|
2. Hydrogen chloride gas does not conduct electricity. |
2. Hydrochloric acid is a good conductor of electricity. |
Question 3: The given set up in the figure is for the preparation of an acid.
(a) Name the acid prepared by this method.
(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 the inverted funnel in the arrangement
Solution 3: 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 a 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.
Question 4: 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 4: 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 5: (a) Name an element which reacts with hydrogen to form a compound which is strongly acidic in water.
(b) Explain why to dilute hydrochloric acid cannot be concentrated by boiling beyond 22.2%.
Solution 5: (a) Chlorine.
The compound formed which is strongly acidic in water is HCl.
H2 + Cl2 → 2HCl
(b) 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°C. When this concentration is reached, no further increase in the concentration of the acid becomes possible by boiling. This is because vapours evolved before 110°C are vapours of water but at a temperature above 110° C vapours consist mostly of molecules of HCl.
Question 6: Hydrochloric acid contains (i) hydrogen (ii) chlorine. Prove it. Write equations for the reactions.
Solution 6: 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 the platinum cathode and a graphite anode. Into the voltameter pour 4 molar HCl and pass direct current.
It is seen that a colourless gas is evolved at the cathode and a greenish gas is evolved at the anode. When a burning splinter is brought near a colourless gas, it bursts into a 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 7: 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 soluble 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 7:
(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 8: 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 8: (a) An aqueous solution of chlorine is acidic as it dissolves in water to form hydrochloric and hypochlorous acids.
till the concentration of the acid reaches 22.2% HCl by weight which boils at 110°C. When this concentration is reached, no further increase in the concentration of the acid becomes possible by boiling. This is because vapours evolved before 110°C are vapours of water but at a temperature above 110° C vapours consist mostly of molecules of HCl.
Question 6: Hydrochloric acid contains (i) hydrogen (ii) chlorine. Prove it. Write equations for the reactions.
Solution 6: 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 the platinum cathode and a graphite anode. Into the voltameter pour 4 molar HCl and pass direct current.
It is seen that a colourless gas is evolved at the cathode and a greenish gas is evolved at the anode. When a burning splinter is brought near a colourless gas, it bursts into a 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 7: 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 soluble 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 7:
(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 8: 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 8: (a) An aqueous solution of chlorine is acidic as it dissolves in water to form hydrochloric and hypochlorous acids.
(b) Silver nitrate reacts with hydrochloric acid to form thick curdy white ppt. of silver chloride whereas silver nitrate does not react with nitric acid.
AgNO3 + HCl → AgCl + HNO3
(White ppt.)
Question 9: Solution A reacts with an acid B (which gives greenish-yellow gas on reacting with oxidizing agents like Pb3O4 to give white precipitate C insoluble in nitric acid but soluble in ammonium hydroxide. Name A, B and C.
Solution 9 : A is Silver nitrate
B is Hydrochloric acid
C is Silver chloride
Question 10: Complete the following reactions and balance them.
(a) NH4OH + HCl →
(b) NaHSO3 + HCl →
(c) Pb(NO3)2 +HCl →
(d) Pb3O4 + HCl →
(e) Zn + 2HCl →
(f) Ca(HCO3)2 + 2HCl →
Solution 10: (a) NH4OH + HCl → NH4Cl + H2O
(b) NaHSO3 + HCl → NaCl + H2O + SO2
(c) Pb(NO3)2 + 2HCl → PbCl2 + 2HNO3
(d) Pb3O4 + 8HCl → 3PbCl2 + 4H2O + Cl2
(e) Zn + 2HCl → ZnCl2 + H2
(f) Ca(HCO3)2 + 2HCl → CaCl2 + 2H2O + 2CO2
Question 11: How will the action of dilute hydrochloric acid enable you to distinguish between the following:
(a) Sodium carbonate and sodium sulphite
(b) sodium thiosulphate and sodium sulphite
Solution 11: (a) Sodium carbonate on treating with dil. HCl results in the formation of sodium chloride with the liberation of carbon dioxide gas.
Na2CO3 + 2HCl → 2NaCl + H2O + CO2 ↑
Sodium sulphite on treating with dil. HCl results in the formation of sodium chloride with the liberation of sulphur dioxide gas.
Na2SO3 + 2HCl → 2NaCl + H2O + SO2 ↑
AgNO3 + HCl → AgCl + HNO3
(White ppt.)
Question 9: Solution A reacts with an acid B (which gives greenish-yellow gas on reacting with oxidizing agents like Pb3O4 to give white precipitate C insoluble in nitric acid but soluble in ammonium hydroxide. Name A, B and C.
Solution 9 : A is Silver nitrate
B is Hydrochloric acid
C is Silver chloride
Question 10: Complete the following reactions and balance them.
(a) NH4OH + HCl →
(b) NaHSO3 + HCl →
(c) Pb(NO3)2 +HCl →
(d) Pb3O4 + HCl →
(e) Zn + 2HCl →
(f) Ca(HCO3)2 + 2HCl →
Solution 10: (a) NH4OH + HCl → NH4Cl + H2O
(b) NaHSO3 + HCl → NaCl + H2O + SO2
(c) Pb(NO3)2 + 2HCl → PbCl2 + 2HNO3
(d) Pb3O4 + 8HCl → 3PbCl2 + 4H2O + Cl2
(e) Zn + 2HCl → ZnCl2 + H2
(f) Ca(HCO3)2 + 2HCl → CaCl2 + 2H2O + 2CO2
Question 11: How will the action of dilute hydrochloric acid enable you to distinguish between the following:
(a) Sodium carbonate and sodium sulphite
(b) sodium thiosulphate and sodium sulphite
Solution 11: (a) Sodium carbonate on treating with dil. HCl results in the formation of sodium chloride with the liberation of carbon dioxide gas.
Na2CO3 + 2HCl → 2NaCl + H2O + CO2 ↑
Sodium sulphite on treating with dil. HCl results in the formation of sodium chloride with the liberation of sulphur dioxide gas.
Na2SO3 + 2HCl → 2NaCl + H2O + SO2 ↑
(b) Sodium thiosulphate reacts with dil. HCl to produce sulphur dioxide gas and precipitates yellow sulphur.
Na2S2O3 + 2HCl → 2NaCl + H2O + SO2 + S ↓
Sulphur is not precipitated when sulphites are treated with dil. HCI.
Question 12: Give three distinct test [apart from using an indicator] you would carry out with a solution of HCl to illustrate the typical properties of an acid.
Solution 12: Three tests are:
HCl gas gives thick white fumes of ammonium chloride when a glass rod dipped in ammonia solution is held near the vapours of the acid.
NH3 + HCl → NH4Cl
With silver nitrate, HCl gives a white precipitate of silver chloride. The precipitate is insoluble in nitric acid but soluble in ammonium hydroxide.
AgNO3 + HCl → AgCl + HNO3
A greenish-yellow gas is liberated when concentrated hydrochloric acid is heated with an oxidizing agent like manganese dioxide.
MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
Question 13: MnO2, PbO2 and red lead react with conc. HCl acid liberates Cl2. What is the common property being shown by these metal oxides?
Solution 13: MnO2, PbO2 and red lead react with conc. HCl acid to liberate Cl2. This shows that hydrochloric acid is oxidized to chlorine by oxidizing agents.
Question 14: Giving reasons state which of the two- a solution of HCl in water or in toluene is an electrolyte.
Solution 14: HCl dissolves both in water and toluene when HCl dissolves in water it ionizes and forms hydronium and chloride ions. Whereas this ionization is not observed in toluene hence a solution of HCl in water can be used as an electrolyte.
Question 15: Convert two soluble metallic nitrates to insoluble metallic chlorides using dil. HCl.
Solution 15: Conversion of metallic nitrates to insoluble metallic chlorides using dil. HCI:
Pb(NO3)2 + 2HCl → PbCl2↓ + PbCI2↓ + 2HNO3↓
Hg2(NO3)2 + 2HCl → Hg2Cl2↓ + 2HNO3
Question 16: State the composition of aqua regia. State which component is the oxidizing agent in aqua regia.
Solution 16: A mixture having three parts of conc. Hydrochloric acid and one part of conc. Nitric acid is called aqua-regia.
Nitric acid acts as an oxidizing agent.
Question 17: Convert hydrochloric acid to nascent chlorine.
Solution 17: Hydrochloric acid can be converted to nascent chlorine by:
3HCl + HNO3 → NOCl + 2H2O + 2[CI]
NOCl: Nascent chlorine
Question 18: Study the flow chart and give balanced equations with conditions for the conversions A, B, C and D.
Solution 18:
Fe + 2HCl → FeCl2 + H2
HCl + NH3 → NH4Cl
PbO2+ 4HCl → PbCl2 + 2H2O + Cl2
Question 19: A solution of hydrogen chloride in water is prepared. The following substances are added to separate portions of the solution:
Solution 19:
Question 20: (a) Write balanced equations.
(i) copper oxide and dilute hydrochloric acid.
(ii) Manganese (iv) oxide and concentrated hydrochloric acid.
(b) (i) Name the experiment illustrated below.
(ii) Which property of hydrogen chloride is demonstrated by this experiment?
(iii) State the colour of the water that has entered the round-bottomed flask.
Solution 20:
(i) CuO + 2HCl → CuCl2 + H2O
(ii) MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
Na2S2O3 + 2HCl → 2NaCl + H2O + SO2 + S ↓
Sulphur is not precipitated when sulphites are treated with dil. HCI.
Question 12: Give three distinct test [apart from using an indicator] you would carry out with a solution of HCl to illustrate the typical properties of an acid.
Solution 12: Three tests are:
HCl gas gives thick white fumes of ammonium chloride when a glass rod dipped in ammonia solution is held near the vapours of the acid.
NH3 + HCl → NH4Cl
With silver nitrate, HCl gives a white precipitate of silver chloride. The precipitate is insoluble in nitric acid but soluble in ammonium hydroxide.
AgNO3 + HCl → AgCl + HNO3
A greenish-yellow gas is liberated when concentrated hydrochloric acid is heated with an oxidizing agent like manganese dioxide.
MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
Question 13: MnO2, PbO2 and red lead react with conc. HCl acid liberates Cl2. What is the common property being shown by these metal oxides?
Solution 13: MnO2, PbO2 and red lead react with conc. HCl acid to liberate Cl2. This shows that hydrochloric acid is oxidized to chlorine by oxidizing agents.
Question 14: Giving reasons state which of the two- a solution of HCl in water or in toluene is an electrolyte.
Solution 14: HCl dissolves both in water and toluene when HCl dissolves in water it ionizes and forms hydronium and chloride ions. Whereas this ionization is not observed in toluene hence a solution of HCl in water can be used as an electrolyte.
Question 15: Convert two soluble metallic nitrates to insoluble metallic chlorides using dil. HCl.
Solution 15: Conversion of metallic nitrates to insoluble metallic chlorides using dil. HCI:
Pb(NO3)2 + 2HCl → PbCl2↓ + PbCI2↓ + 2HNO3↓
Hg2(NO3)2 + 2HCl → Hg2Cl2↓ + 2HNO3
Question 16: State the composition of aqua regia. State which component is the oxidizing agent in aqua regia.
Solution 16: A mixture having three parts of conc. Hydrochloric acid and one part of conc. Nitric acid is called aqua-regia.
Nitric acid acts as an oxidizing agent.
Question 17: Convert hydrochloric acid to nascent chlorine.
Solution 17: Hydrochloric acid can be converted to nascent chlorine by:
3HCl + HNO3 → NOCl + 2H2O + 2[CI]
NOCl: Nascent chlorine
Question 18: Study the flow chart and give balanced equations with conditions for the conversions A, B, C and D.
Solution 18:
HCl + NH3 → NH4Cl
PbO2+ 4HCl → PbCl2 + 2H2O + Cl2
Question 19: A solution of hydrogen chloride in water is prepared. The following substances are added to separate portions of the solution:
Solution 19:
|
Sl. No. |
Substance added |
Gas evolved |
Odour |
|
1. |
Calcium carbonate |
Carbon dioxide |
Odourless |
|
2. |
Magnesium |
Hydrogen |
Odourless |
|
3. |
Manganese (IV) oxide with heating |
Cl2 |
Strong Pungent odour |
|
4. |
Sodium sulphide |
Hydrogen sulphide |
Rotten egg |
Question 20: (a) Write balanced equations.
(i) copper oxide and dilute hydrochloric acid.
(ii) Manganese (iv) oxide and concentrated hydrochloric acid.
(b) (i) Name the experiment illustrated below.
(iii) State the colour of the water that has entered the round-bottomed flask.
Solution 20:
(i) CuO + 2HCl → CuCl2 + H2O
(ii) MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
(b) (i) The experiment is called Fountain Experiment.
(ii) This experiment shows that hydrogen chloride is highly soluble in water.
(iii) Red
Question 21: Write balanced equations for the reaction of dilute hydrochloric acid with each of the following:
(a) iron
(b) sodium hydrogen carbonate,
(c) iron (II) sulphide
(d) sodium sulphite
(e) sodium thiosulphate solution
Solution 21: (i) Fe + 2HCl → FeCl2 + H2
(ii) NaHCO3 + HCl → NaCl + H2O + CO2
(iii) FeS + 2HCl → FeCl2 + H2S
(iv) Na2SO3 + 2HCl → 2NaCl + H2O + SO2
(v) Na2S2O3 + 2HCl → 2NaCl + H2O + SO2 + S
Question 22: What property of hydrogen chloride is demonstrated when it is collected by downward delivery (upward displacement)?
Solution 22: When hydrogen chloride is collected by downward delivery or upward displacement, it shows that it is heavier than air.
Question 23: Why is hydrogen chloride not collected over water?
Solution 23: Hydrogen chloride is not collected over water as it is soluble in water.
Question 24: Write the equations for the following reactions:
(a) Dilute hydrochloric acid and sodium thiosulphate,
(b) Dilute hydrochloric acid and lead nitrate solution.
Solution 24: (i) Na2S2O3 + 2HCl → 2NaCl + H2O + SO2 + S
(ii) Pb(NO3)2 + 2HCl → PbCl2 + 2HNO3
(ii) This experiment shows that hydrogen chloride is highly soluble in water.
(iii) Red
Question 21: Write balanced equations for the reaction of dilute hydrochloric acid with each of the following:
(a) iron
(b) sodium hydrogen carbonate,
(c) iron (II) sulphide
(d) sodium sulphite
(e) sodium thiosulphate solution
Solution 21: (i) Fe + 2HCl → FeCl2 + H2
(ii) NaHCO3 + HCl → NaCl + H2O + CO2
(iii) FeS + 2HCl → FeCl2 + H2S
(iv) Na2SO3 + 2HCl → 2NaCl + H2O + SO2
(v) Na2S2O3 + 2HCl → 2NaCl + H2O + SO2 + S
Question 22: What property of hydrogen chloride is demonstrated when it is collected by downward delivery (upward displacement)?
Solution 22: When hydrogen chloride is collected by downward delivery or upward displacement, it shows that it is heavier than air.
Question 23: Why is hydrogen chloride not collected over water?
Solution 23: Hydrogen chloride is not collected over water as it is soluble in water.
Question 24: Write the equations for the following reactions:
(a) Dilute hydrochloric acid and sodium thiosulphate,
(b) Dilute hydrochloric acid and lead nitrate solution.
Solution 24: (i) Na2S2O3 + 2HCl → 2NaCl + H2O + SO2 + S
(ii) Pb(NO3)2 + 2HCl → PbCl2 + 2HNO3