Study of Compounds — Sulphuric Acid

Solutions for Chemistry, Class 10, ICSE

Exercise 11 Long Answer Type

2 questions

Question 1

What property of conc. H₂SO₄ is made use of in each of the following cases? Give an equation for the reaction in each case:

(a) in the production of HCl gas when it reacts with a chloride,

(b) in the preparation of CO from HCOOH.

(d) in the preparation of sulphur dioxide by warming a mixture of conc. sulphuric acid and copper-turnings.

(e) hydrogen chloride gas is passed through concentrated sulphuric acid.

(f) it's reaction with (i) Ethanol (ii) Carbon.

Exercise 11 Long Answer Type

Answer:

(a) The property of being a non-volatile acid is used.

NaCl + H₂SO₄ [conc.] $\xrightarrow{\lt 200 \degree\text{C}}$ NaHSO₄ + HCl

(b) The property of being a dehydrating agent is used.

HCOOH $\xrightarrow{\text{Conc. H}_2\text{SO}_4}$ CO + H₂O

Mg + H₂SO₄ [dil.] ⟶ MgSO₄ + H₂ ↑

(d) The property of being an oxidizing agent is used.

Cu + 2H₂SO₄ [conc.] ⟶ CuSO₄ + 2H₂O + SO₂ ↑

(e) The property of being a drying agent is used.

Hydrogen chloride gas is dried by passing through conc. sulphuric acid as it does not react with conc. sulphuric acid.

(f) (i) The property of being a dehydrating agent is used.

$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170\degree\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} ↑ + \text{H}_2\text{O}\$

(ii) The property of being an oxidizing agent is used.

C + 2H₂SO₄ [conc.] ⟶ CO₂ + 2H₂O + 2SO₂ ↑

Question 2

(a) Which property of sulphuric acid accounts for it's use as a dehydrating agent?

(b) Concentrated sulphuric acid is both an oxidizing agent and a non-volatile acid. Write one equation each to illustrate the above mentioned properties of sulphuric acid.

Exercise 11 Long Answer Type

Answer:

(a) Sulphuric acid is a powerful dehydrating agent due to it's strong affinity towards water.

(b) (i) Oxidising agent : The oxidising property of concentrated sulphuric acid is due to the fact that on thermal decomposition it yields nascent oxygen [O].

H₂SO₄ ⟶ H₂O + SO₂ + [O]

Nascent oxygen oxidises non-metals, metals and inorganic compounds.

C + 2H₂SO₄ ⟶ CO₂ + 2H₂O + 2SO₂ ↑

(ii) Non-volatile nature : It has a high boiling point so it is considered to be a non-volatile acid. It is, therefore, used for preparing volatile acids like hydrochloric acid, nitric acid and acidic acid from their salts by double decomposition.

NaCl + H₂SO₄ ⟶ NaHSO₄ + HCl

Exercise 11 Multiple Choice Type

20 questions

Question 1

The gas evolved when dil. sulphuric acid reacts with iron sulphide.

Hydrogen sulphide
Sulphur dioxide
Sulphur trioxide
Vapour of sulphuric acid.

Exercise 11 Multiple Choice Type

Answer:

Hydrogen sulphide

Reason —

FeS + H₂SO₄ [dil.] ⟶ FeSO₄ + H₂S

Question 2

In the given equation :

H₂S + 2H₂SO₄ ⟶ S + 2H₂O + SO₂

Identify the role played by conc. H₂SO₄

Non-volatile acid
Oxidising agent
Dehydrating agent
None of the above.

Exercise 11 Multiple Choice Type

Answer:

Oxidising agent

Reason — The oxidising property of concentrated sulphuric acid leads to its thermal decomposition, and yields nascent oxygen [O]. In the above reaction, Hydrogen sulphide is oxidised by this nascent oxygen released from sulphuric acid.

Question 3

Dilute sulphuric acid will produce a white ppt. when added to a solution of:

Copper nitrate
Zinc nitrate
Lead nitrate
Sodium nitrate

Exercise 11 Multiple Choice Type

Answer:

Lead nitrate

Reason —

Pb(NO₃)₂ + H₂SO₄ (dil) ⟶ 2HNO₃ + PbSO₄ ↓ [white ppt. formed]

White ppt. of PbSO₄ is visible.

Question 4

On passing SO₂ through chlorine water, the acid produced is :

H₂SO₃
HNO₃
H₂SO₄
H₂PO₄

Exercise 11 Multiple Choice Type

Answer:

H₂SO₄

Reason — On passing SO₂ through chlorine water, oxidation of aqueous solution of sulphur dioxide takes place and H₂SO₄ is formed.

SO₂ + H₂O + Cl₂ ⟶ H₂SO₄ + 2HCl

Question 5

When HCl is prepared by the reaction of NaCl with H₂SO₄, the property of H₂SO₄ exhibited is :

Dehydrating agent
Drying agent
Oxidising property
Non volatile acid

Exercise 11 Multiple Choice Type

Answer:

Non volatile acid

Reason — Concentrated sulphuric acid is used for preparing volatile acid hydrochloric acid from their salts by double decomposition, because sulphuric acid is considered to be a non-volatile acid with high boiling point (338 °C).

Question 6

The catalyst preferred in contact process is :

Pt
V₂O₅
Fe
Pd

Exercise 11 Multiple Choice Type

Answer:

V₂O₅

Reason — The catalyst preferred in contact process is vanadium pentoxide (V₂O₅). It is highly efficient at converting SO₂ to SO₃.

Question 7

The substance added to SO₃ to manufacture H₂SO₄ by contact process is :

H₂O
H₂SO₄
H₂S₂O₇
H₂S

Exercise 11 Multiple Choice Type

Answer:

H₂SO₄

Reason — The substance added to SO₃ to manufacture H₂SO₄ by contact process is H₂SO₄. Sulphur trioxide on dissolving in water can produce sulphuric acid, but it does not dissolve in water satisfactorily and it gives a lot of heat and forms misty droplets of sulphuric acid so it is not directly absorbed by water. It is first absorbed by sulphuric acid to produce oleum. oleum is further diluted to produce H₂SO₄.

Question 8

The role of sulphuric acid in the reaction given below is :

S + 2H₂SO₄ ⟶ 3SO₂ + 2H₂O

Non volatile acid
Oxidising agent
Dehydrating agent
None of the above

Exercise 11 Multiple Choice Type

Answer:

Oxidising agent

Reason — The oxidising property of concentrated sulphuric acid leads to its thermal decomposition, and yields nascent oxygen [O]. In the above reaction, sulphur is oxidised by this nascent oxygen released from sulphuric acid.

Question 9

Dilute H₂SO₄ and conc. H₂SO₄ can be distinguished by :

Copper
Silver
Gold
Platinum

Exercise 11 Multiple Choice Type

Answer:

Copper

Reason — Dilute H₂SO₄ and conc. H₂SO₄ can be distinguished by Copper. Copper does not react with dilute H₂SO₄, because dilute H₂SO₄ cannot act as an oxidising agent. Whereas, conc. sulphuric acid on heating with copper evolves sulphur dioxide.

Question 10

On adding conc. H₂SO₄ to cane sugar, the colour observed is :

yellow
black
green
violet

Exercise 11 Multiple Choice Type

Answer:

black

Reason — On adding conc. H₂SO₄ to cane sugar (carbohydrate), they react immediately to give a black spongy mass of carbon.

Question 11

The acid which produces charcoal from sugar is :

conc. HNO₃
conc. HCl
Conc. H₂SO₄
conc. H₃PO₄

Exercise 11 Multiple Choice Type

Answer:

Conc. H₂SO₄

Reason — All carbohydrates react with Conc. H₂SO₄ immediately to give a black spongy mass of carbon. Carbon obtained in this reaction is very pure and is called as sugar charcoal.

Question 12

The substance which can be used as drying as well as dehydrating agent is :

conc. H₂SO₄
conc. HNO₃
Conc. HCl
conc. H₂CO₃

Exercise 11 Multiple Choice Type

Answer:

Conc. H₂SO₄

Reason — Conc. H₂SO₄ has a great affinity for water. It readily removes chemically combined water molecules i.e., elements of water from other compounds. Hence, it acts as drying as well as dehydrating agent.

Question 13

The compound formed by the oxidation of sulphur by nitric acid is :

P — Sulphuric acid

Q — Nitrogen dioxide

R — Sulphur dioxide

Only P
Only Q
Only R
Both P and Q

Exercise 11 Multiple Choice Type

Answer:

Both P and Q

Reason — The compounds formed by the oxidation of sulphur by nitric acid are Sulphuric acid (H₂SO₄) and Nitrogen dioxide (NO₂).

S + 6HNO₃ ⟶ H₂SO₄ + 6NO₂ + 2H₂O

Question 14

Assertion (A): Sulphuric acid is known as the oil of vitriol.

Reason (R): Sulphuric acid was first obtained by heating crystals of green vitriol.

Both A and R are true and R is the correct explanation of A.
Both A and R are true but R is not the correct explanation of A.
A is true but R is false.
A is false but R is true.

Exercise 11 Multiple Choice Type

Answer:

Both A and R are true and R is the correct explanation of A.

Explanation— Sulphuric acid is referred to as Oil of vitriol because in the later middle ages, it was obtained as an oily viscous liquid by heating crystals of green vitriol. Hence, the assertion (A) is true.
Sulphuric acid was first obtained by heating crystals of green vitriol. Hence, reason (R) is true.

Reason (R) explains why sulphuric acid is known as the oil of vitriol. Hence, reason (R) is the correct explanation of assertion (A).

Question 15

Assertion (A): V₂O₅ or Pt is used in the catalytic oxidation of sulphur dioxide

Reason (R): The catalytic oxidation of SO₂ is an exothermic reaction, so it requires to be heated to about 450°C only in the beginning.

Both A and R are true and R is the correct explanation of A.
Both A and R are true but R is not the correct explanation of A.
A is true but R is false.
A is false but R is true.

Exercise 11 Multiple Choice Type

Answer:

Both A and R are true but R is not the correct explanation of A.

Explanation— In the catalytic oxidation of sulphur dioxide, vanadium pentoxide (V₂O₅) or platinum (Pt) is used as a catalyst. Hence, the assertion (A) is true.
The catalytic oxidation of sulphur dioxide is highly exothermic, the catalyst is heated only in the beginning to about 450°C. This temperature is maintained by the heat evolved during the reaction. Hence, the reason (R) is true.

Reason (R) doesn't explain why V₂O₅ or Pt is used as the catalyst. Hence, reason (R) is not the correct explanation of assertion (A).

Question 16

Assertion (A): Sulphuric acid when dissolved in water forms a basic salt

Reason (R): Sulphuric acid ionises in two stages, it is a dibasic acid.

Both A and R are true and R is the correct explanation of A.
Both A and R are true but R is not the correct explanation of A.
A is true but R is false.
A is false but R is true.

Exercise 11 Multiple Choice Type

Answer:

A is false but R is true.

Explanation— Sulphuric acid when dissolved in water forms hydronium ion and shows acidic properties. Hence, the assertion (A) is false.

Sulphuric acid ionises in two stages and is called dibasic acid. Hence, the reason (R) is true.

H₂SO₄ + 2H₂O $\rightleftharpoons$ H₃O⁺ + HSO₄^-

HSO₄^- + 2H₂O $\rightleftharpoons$ H₃O⁺ + SO₄^2-

Question 17

Assertion (A): Pure sulphuric acid is almost a non-conductor of electricity.

Reason (R): Dilute sulphuric acid is a good conductor of electricity.

Both A and R are true and R is the correct explanation of A.
Both A and R are true but R is not the correct explanation of A.
A is true but R is false.
A is false but R is true.

Exercise 11 Multiple Choice Type

Answer:

Both A and R are true but R is not the correct explanation of A.

Explanation— Pure (concentrated) H₂SO₄ is not ionized significantly because no water is present to dissociate it into ions. Therefore, it does not conduct electricity. Hence, the assertion (A) is true.
When H₂SO₄ is diluted with water, it ionizes completely to give H^- and SO₄^2- ions, which are free to move. These ions carry electric current, making it a strong electrolyte. Hence, the reason (R) is true.

However, reason (R) does not explain why pure sulphuric acid is a poor conductor of electricity. Hence, reason (R) is not the correct explanation of assertion (A).

Question 18

Assertion (A): Impurity of arsenic oxide must be removed before passing the mixture of SO₂ and air through the catalytic chamber.

Reason (R): Arsenic oxide poisons the catalyst.

Both A and R are true and R is the correct explanation of A.
Both A and R are true but R is not the correct explanation of A.
A is true but R is false.
A is false but R is true.

Exercise 11 Multiple Choice Type

Answer:

Both A and R are true and R is the correct explanation of A.

Explanation— In the manufacture of sulphuric acid, purification of gases is done by removing the impurity of arsenic oxide before passing the mixture of SO₂ and air through the catalytic chamber. Hence, the assertion (A) is true.
Purification of gases is done because arsenic oxide poisons the catalyst and the catalyst loses its efficiency. Hence, the reason (R) is true and it is the correct explanation of assertion (A).

Question 19

Assertion (A): Concentrated sulphuric acid is kept in air tight bottles.

Reason (R): Air contains impurities, therefore H₂SO₄ will get spoiled.

Both A and R are true and R is the correct explanation of A.
Both A and R are true but R is not the correct explanation of A.
A is true but R is false.
A is false but R is true.

Exercise 11 Multiple Choice Type

Answer:

A is true but R is false.

Explanation— As concentrated sulphuric acid is hygroscopic and has a great affinity for water hence, it absorbs moisture from the atmosphere. Therefore, it is kept in air tight bottles. Hence, the assertion (A) is true.
The main concern to keep sulphuric acid in air tight bottles is to avoid moisture from entering, not impurities. Impurities in air do not significantly affect concentrated sulphuric acid. Hence, the reason (R) is false.

Question 20

Assertion (A): Sulphuric acid acts as an oxidising agent.

Reason (R): Sulphuric acid produces hydrogen on reacting with zinc.

Both A and R are true and R is the correct explanation of A.
Both A and R are true but R is not the correct explanation of A.
A is true but R is false.
A is false but R is true.

Exercise 11 Multiple Choice Type

Answer:

Both A and R are true but R is not the correct explanation of A.

Explanation— Sulphuric acid acts as an oxidising agent due to the fact that on thermal decomposition, it yields nascent oxygen [O]. This nascent oxygen oxidises non-metals, metals and inorganic compounds. Hence, the assertion (A) is true.

H₂SO₄ ⟶ 2H₂O + SO₂ + [O]

Dilute sulphuric acid reacts with metals like zinc, that is present above hydrogen in the activity series to form metallic sulphate and hydrogen at ordinary temperature. Hence, the reason (R) is true.

Zn + H₂SO₄ ⟶ ZnSO₄ + H₂ ↑

But, reason (R) doesn't explain the reason behind oxidising property of sulphuric acid. Hence, reason (R) is not the correct explanation of assertion (A).

Exercise 11 Short Answer Type

14 questions

Question 1

Give reasons for the following.

(a) Sulphuric acid forms two types of salts with NaOH.

(b) A piece of wood becomes black when concentrated sulphuric acid is poured on it.

Exercise 11 Short Answer Type

Answer:

(a) Sulphuric acid forms two types of salts i.e., acid salt and normal salt with an NaOH (alkali) since it's basicity is two.

NaOH [insufficient] + H₂SO₄ ⟶ H₂O + NaHSO₄ [acid salt]

2NaOH [excess] + H₂SO₄ ⟶ 2H₂O + Na₂SO₄ [normal salt]

(b) A piece of wood becomes black because of the dehydrating property of sulphuric acid. It readily removes elements of water from other compounds.

$[\text{C}_{6}\text{H}_{10}\text{O}_{5}]\text{n}\xrightarrow{\text{Conc. H}_2\text{SO}_4} \text{6[C]}_\text{n} + \text{5[H}_2\text{O}]_\text{n}$

(c) When oil vitriol is added to sodium carbonate brisk effervescence are seen due to the evolution of Carbon dioxide.

Na₂CO₃ + H₂SO₄ ⟶ H₂O + Na₂SO₄ + CO₂ ↑

Question 2

Why is water not added to concentrated H₂SO₄ in order to dilute it?

Exercise 11 Short Answer Type

Answer:

Water is never poured on concentrated H₂SO₄ to dilute it as large amount of heat is evolved which changes poured water to steam. The steam so formed causes spurting of acid which can cause burn injuries, so dilution is done by pouring acid on a given amount of water in a controlled manner by continuous stirring, else acid being heavier will settle down. The evolved heat is dissipated in the water itself and hence the spurting of the acid is minimized.

Question 3

Why is:

(a) Concentrated sulphuric acid kept in air-tight bottles?

(b) H₂SO₄ is not used as a drying agent for H₂S?

Exercise 11 Short Answer Type

Answer:

(a) As concentrated sulphuric acid is hygroscopic and has a great affinity for water hence, it absorbs moisture from the atmosphere. Therefore, it is kept in air tight bottles.

(b) Sulphuric acid is not a drying agent for H₂S because it reacts with H₂S to form sulphur.
H₂S + H₂SO₄ ⟶ S + 2H₂O + SO₂ ↑

(c) Concentrated sulphuric acid has a high boiling point (338°C) and so it is considered to be a non-volatile acid. It is, therefore, used for preparing volatile acids like hydrochloric acid and nitric acid from their salts by double decomposition.

NaCl + H₂SO₄ [conc.] $\xrightarrow{\lt 200 \degree\text{C}}$ NaHSO₄ + HCl

NaNO₃ + H₂SO₄ [conc.] $\xrightarrow{\lt 200 \degree\text{C}}$ NaHSO₄ + HNO₃

Question 4

State your observation when –

(a) Sugar crystals are added to a hard glass test tube containing conc. sulphuric acid.

(b) Conc. H₂SO₄ is added to a crystal of hydrated copper sulphate.

Exercise 11 Short Answer Type

Answer:

(a) Steam is evolved from the test tube and it becomes very hot. Black spongy mass of carbon is formed.

$\underset{\text{Cane Sugar}}{\text{C}_{12}\text{H}_{22}\text{O}_{11}} \text{ (s)} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{Sugar Charcoal}}{12\text{C (s)}} + 11\text{H}_2\text{O}$

(b) The blue coloured hydrous copper sulphate changes to white anhydrous copper sulphate as the water of crystallization is removed.

$\text{CuSO}_4\text{.5H}_2\text{O} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \text{CuSO}_4 \text{ [White Anhydrous]} + 5\text{H}_2\text{O}$

Question 5

Give balanced equation(s) for :

(a) Reaction of dilute sulphuric acid when poured over sodium sulphite

(b) Manufacture of sulphuric acid by the Contact process.

(d) Dehydration of sugar crystals by conc. sulphuric acid

(e) Action of concentrated sulphuric acid on carbon.

Exercise 11 Short Answer Type

Answer:

(a) Na₂SO₃ + H₂SO₄ (dil.) ⟶ Na₂SO₄ + H₂O + SO₂

(b) Contact process:

Sulphur or Pyrite Burner:
S + O₂ ⟶ SO₂
4FeS₂ + 11O₂ ⟶ 2Fe₂O₃ + 8SO₂

Contact Tower :

$2\text{SO}_2 + \text{O}_2 \xrightleftharpoons[450-500\text{\degree C }/1 - 2 \text{ atmos}]{\text{V}_2\text{O}_5} 2\text{SO}_3 + 45 \text{ K cals}$

Absorption Tower :
SO₃ + H₂SO₄ ⟶ H₂S₂O₇

Dilution Tank:
H₂S₂O₇ + H₂O ⟶ 2H₂SO₄

(d) $\underset{\text{Cane Sugar}}{\text{C}<em>{12}\text{H}</em>{22}\text{O}_{11}} \text{ (s)} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{Sugar Charcoal}}{12\text{C (s)}} + 11\text{H}_2\text{O}$

(e) C + 2H₂SO₄ [conc.] ⟶ CO₂ + 2H₂O + 2SO₂

Question 6

Write the equations for the following reactions:

(a) dil. H₂SO₄ and barium chloride.

(b) dil. H₂SO₄ and sodium sulphide.

Exercise 11 Short Answer Type

Answer:

(a) BaCl₂ + H₂SO₄ (dil) ⟶ 2HCl + BaSO₄ ↓ [white ppt. formed]

(b) Na₂S + H₂SO₄ ⟶ Na₂SO₄ + H₂S

Question 7

Dilute and concentrated sulphuric acid can be distinguished by using metals copper and zinc. Explain by giving balanced equations.

Exercise 11 Short Answer Type

Answer:

Conc. sulphuric acid acts as an oxidising agent and oxidises metals like copper and Zinc.

Cu + 2H₂SO₄ (conc.) ⟶ CuSO₄ + H₂O + 2SO₂ ↑

Zn + 2H₂SO₄ (conc.) ⟶ ZnSO₄ + H₂O + 2SO₂ ↑

Whereas, dil. sulphuric acid is not an oxidising agent and it cannot oxidise copper and zinc.

Hence, Conc. sulphuric acid and dil. sulphuric acid can be distinguished by considering the oxidising property of sulphuric acid.

Question 8

Give two balanced reactions of each type to show the following properties of sulphuric acid:

(a) Acidic nature

(b) Oxidising agent

(d) Non-volatile nature

Exercise 11 Short Answer Type

Answer:

(a) Acidic nature

Mg + H₂SO₄ (dil.) ⟶ MgSO₄ + H₂ ↑
Zn + H₂SO₄ (dil.) ⟶ ZnSO₄ + H₂ ↑

(b) Oxidising agent

C + 2H₂SO₄ ⟶ CO₂ + 2H₂O + 2SO₂ ↑
Zn + 2H₂SO₄ ⟶ ZnSO₄ + 2H₂O + SO₂ ↑

$\text{HCOOH} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \text{CO} + \text{H}_2\text{O}$
$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170\degree\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} ↑ + \text{H}_2\text{O}$

(d) Non-volatile Nature

NaCl + H₂SO₄ ⟶ NaHSO₄ + HCl
KCl + H₂SO₄ ⟶ KHSO₄ + HCl

Question 9

Give a chemical test to distinguish between:

(a) dilute sulphuric acid and dilute hydrochloric acid (using lead nitrate solution).

(b) dilute sulphuric acid and concentrated sulphuric acid.

Exercise 11 Short Answer Type

Answer:

(a) When dil sulphuric acid is reacted with lead nitrate it produces a white ppt. of lead sulphate which remains insoluble even on heating.

Pb(NO₃)₂ + H₂SO₄ (dil) ⟶ 2HNO₃ + PbSO₄ ↓ [white ppt. formed]

When dil hydrochloric acid is reacted with lead nitrate, a white ppt. of lead chloride is formed which dissolves on heating.

Pb(NO₃)₂ + 2HCl ⟶ 2HNO₃ + PbCl₂ ↓ [white ppt. formed]

(b) Dilute sulphuric acid when reacted with zinc produces Hydrogen gas which burns with a pop sound.

Zn + H₂SO₄ [dil.] ⟶ ZnSO₄ + H₂ ↑

Concentrated sulphuric acid when reacted with zinc produces SO₂ gas which turns acidified potassium dichromate paper green.

Zn + 2H₂SO₄ [conc.] ⟶ ZnSO₄ + 2H₂O + SO₂ ↑

(c) Barium chloride soln. reacts with dilute sulphuric acid to give a white ppt. of barium sulphate (BaSO₄) but with dilute hydrochloric acid no white ppt. is produced since barium chloride is soluble in dil. sulphuric acid.

H₂SO₄ (dil.) + BaCl₂ (aq.) ⟶ 2HCl + BaSO₄ ↓ [white ppt. formed]

HCl (dil.) + BaCl₂ (aq.) ⟶ No reaction

Question 10

State the conditions required for the conversion of sulphur dioxide to sulphur trioxide to take place:

Exercise 11 Short Answer Type

Answer:

The conditions for the conversion of sulphur dioxide to sulphur trioxide are:

Temperature — 450 to 500°C
Pressure — 1 to 2 atmosphere
Presence of Catalyst — Vanadium pentoxide (V₂O₅)
Excess of Oxygen

Question 11

Making use only of substances given: dil. sulphuric acid, Sodium carbonate, Zinc, Sodium Sulphite, Lead, Calcium carbonate:

Give equations for the reactions by which you could obtain:

(a) hydrogen

(b) sulphur dioxide

(d) zinc carbonate (2 steps)

Exercise 11 Short Answer Type

Answer:

(a) Zn + H₂SO₄ [dil.] ⟶ ZnSO₄ + H₂

(b) Na₂SO₃ + H₂SO₄ [dil.] ⟶ Na₂SO₄ + H₂O + SO₂

(d) Zn + H₂SO₄ [dil.] ⟶ ZnSO₄ + H₂
ZnSO₄ + Na₂CO₃ [dil.] ⟶ ZnCO₃ + Na₂SO₄

Question 12

Give equations for the action of sulphuric acid on —

(a) Potassium hydrogen carbonate.

(b) Sulphur

Exercise 11 Short Answer Type

Answer:

(a) 2KHCO₃ + H₂SO₄ ⟶ K₂SO₄ + 2H₂O + 2CO₂

(b) S + 2H₂SO₄ (conc.) ⟶ 3SO₂ + 2H₂O

Question 13

In the manufacture of sulphuric acid by the Contact process, give the equations for the conversion of sulphur trioxide to sulphuric acid.

Exercise 11 Short Answer Type

Answer:

SO₃ + H₂SO₄ ⟶ H₂S₂O₇

H₂S₂O₇ + H₂O ⟶ 2H₂SO₄

Question 14

Give a balanced equation for the conversion of zinc oxide to zinc sulphate.

Exercise 11 Short Answer Type

Answer:

ZnO + H₂SO₄ [dil.] ⟶ ZnSO₄ + H₂O

Exercise 11 Very Short Answer Type

9 questions

Question 1

Following are the typical properties of dilute acid. Complete them by inserting suitable words:

(a) Active metal + acid ⟶ ............... + ...............

(b) Base + Acid ⟶ ............... + ...............

(d) Sulphite/hydrogen sulphite + Acid ⟶ ............... + ...............

(e) Sulphide + Acid ⟶ ............... + ...............

Exercise 11 Very Short Answer Type

Answer:

(a) Active metal + acid ⟶ metallic salt + hydrogen gas

(b) Base + Acid ⟶ salt + water

(d) Sulphite/hydrogen sulphite + Acid ⟶ salt + water + sulphur dioxide

(e) Sulphide + Acid ⟶ salt + hydrogen sulphide

Question 2

Name :

(a) The acid formed when sulphur dioxide dissolves in water.

(b) The gas released when sodium carbonate is added to a solution of sulphur dioxide.

(d) The gas that can be oxidized to sulphur.

(e) The solution which liberates sulphur dioxide gas from sodium sulphite.

(f) The gas produced on reaction of dilute sulphuric acid with a metallic sulphide.

(g) A dilute mineral acid which forms a white precipitate when treated with barium chloride solution.

(h) The acid which produces sugar charcoal from sugar.

(i) The acid on mixing with lead nitrate solution produces white ppt. which is insoluble even on heating.

Exercise 11 Very Short Answer Type

Answer:

(a) Sulphurous acid

(b) Carbon dioxide gas

(d) Hydrogen sulphide gas (H₂S)
H₂S + H₂SO₄ [conc.] ⟶ S + SO₂ + 2H₂O

(e) Dilute sulphuric acid.

(f) Hydrogen sulphide (H₂S)

(g) Dilute sulphuric acid.
BaCl₂ + H₂SO₄ (dil) ⟶ 2HCl + BaSO₄ ↓ [white ppt. formed]

(h) Conc. sulphuric acid

(i) Dilute sulphuric acid

Question 3

What is the name given to the salts of:

(a) Sulphurous acid

(b) Sulphuric acid

Exercise 11 Very Short Answer Type

Answer:

(a) Sulphite

(b) Sulphate

Question 4

What property of conc. H₂SO₄

(a) is used in the action when sugar turns black in it's presence.

(b) allows it to be used in the preparation of HCl and HNO₃ acids.

Exercise 11 Very Short Answer Type

Answer:

(a) Dehydrating agent.
C₁₂H₂₂O₁₁ + nH₂SO₄ ⟶ 12C + 11H₂O

(b) Conc. H₂SO₄ is a non-volatile acid.

Question 5

State the property of sulphuric acid shown by the reaction of conc. sulphuric acid when heated with

(a) Potassium nitrate

(b) Carbon

Exercise 11 Very Short Answer Type

Answer:

(a) Sulphuric acid behaves as a non-volatile acid.

$\text{KNO}_3 + \text{H}_2\text{SO}_4 [\text{conc.}]\xrightarrow{\lt 200 \degree\text{C}} \text{KHSO}_\text{4} + \text{HNO}_\bold{3}$

(b) Sulphuric acid behaves as an oxidizing agent

C + 2H₂SO₄ ⟶ CO₂ + 2H₂O + 2SO₂

C₂H₅OH $\xrightarrow[170\degree\text{C}]{\text{Conc. H}_2\text{SO}_4}$ C₂H₄↑ + H₂O

Question 6

Some properties of sulphuric acid are listed below. Choose the property A, B, C or D which is responsible for the reactions (i) to (v). Some properties may be repeated:

A. Typical acid

B. Dehydrating agent

C. Non-volatile acid

D. Oxidising agent

(i) C₁₂H₂₂O₁₁ + nH₂SO₄ ⟶ 12C + 11H₂O + nH₂SO₄

(ii) S + 2H₂SO₄ ⟶ 3SO₂ + 2H₂O

(iii) NaCl + H₂SO₄ ⟶ NaHSO₄ + HCl

(iv) CuO + H₂SO₄ ⟶ CuSO₄ + H₂O

(v) Na₂CO₃ + H₂SO₄ ⟶ Na₂SO₄ + H₂O + CO₂

Exercise 11 Very Short Answer Type

Answer:

(i) Dehydrating agent

(ii) Oxidising agent

(iii) Non-volatile acid

(iv) Typical acid

(v) Typical acid

Question 7

Some properties of sulphuric acid are listed below. Choose the role played by sulphuric acid – A, B, C, or D which is responsible for the reactions (i) to (v).

Some role/s may be repeated.

(A) Dilute acid

(B) Dehydrating agent

(D) Oxidising agent

(a) $\text{CuSO}_4.5\text{H}_2\text{O} \xrightarrow{\text{Conc. H}_2 \text{SO}_4} \text{CuSO}_4 + 5\text{H}_2\text{O}$

(b) S + 2H₂SO₄ [conc.] ⟶3SO₂ + 2H₂O

(c) $\text{NaNO}_3 + \text{H}_2\text{SO}_4 [\text{conc.}]\xrightarrow{\lt 200 \degree\text{C}} \text{NaHSO}_\text{4} + \text{HNO}_\bold{3}$

(d) MgO + H₂SO₄ ⟶ MgSO₄ + H₂O

(e) Zn + 2H₂SO₄ [conc.] ⟶ ZnSO₄ + SO₂ + 2H₂O

Exercise 11 Very Short Answer Type

Answer:

(a) B: Dehydrating agent

(b) D: Oxidizing agent

(d) A: Dilute acid

(e) D: Oxidising agent

Question 8

Copy and complete the following table relating to an important industrial process and it's final output.

Name of process	Inputs	Catalyst	Equation for catalyzed reaction	Output
Contact Process	Sulphur dioxide + oxygen

Exercise 11 Very Short Answer Type

Answer:

Name of process	Inputs	Catalyst	Equation for catalyzed reaction	Output
Contact Process	Sulphur dioxide + oxygen	Vanadium pentoxide [V₂O₅] or platinum [Pt.]	$2\text{SO}_2 + \text{O}_2 \xrightleftharpoons [450-500\text{\degree C }/1 - 2 \text{ atmos}]{\text{V}_2\text{O}_5} 2\text{SO}_3 + \text{45 K cals}$	Sulphuric acid

Question 9

Copy and complete the following table:

Column 1 Substance reacted with acid	Column 2 Dilute or concentrated acid	Column 3 Gas
		Hydrogen
		Carbon dioxide
		Only chlorine

Exercise 11 Very Short Answer Type

Answer:

Column 1 Substance reacted with acid	Column 2 Dilute or concentrated acid	Column 3 Gas
*Magnesium*	*Dilute sulphuric acid*	Hydrogen
*Sodium carbonate*	*Dilute sulphuric acid*	Carbon dioxide
*Bleaching powder CaOCl₂*	*Dilute sulphuric acid*	Only chlorine

Intext Questions

4 questions

Question 1

Comment, sulphuric acid is referred to as:

(a) King of chemicals

(b) Oil of Vitriol

Intext Questions

Answer:

(a) Sulphuric acid is referred as the King of Chemicals because there is no other manufactured compound which is used by such a large number of key industries. It has been known for a long time.

(b) Sulphuric acid is referred to as Oil of vitriol because in the later middle ages, 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.

(d) Why H₂SO₄ is not obtained by directly reacting SO₃ with water?

(e) Name the chemical used to dissolve SO₃ and also name the product formed. Give all the main reactions of this product.

Intext Questions

Answer:

(a) 4FeS₂ (iron pyrite) + 11O₂ ⟶ 2Fe₂O₃ + 8SO₂ ↑

S + O ⟶ SO₂ ↑

(b) The conditions for the oxidation of SO₂ are:

The temperature should be as low as possible. The yield has been found to be maximum at about 410 ⁰C – 450 ⁰C.
High pressure favours the reaction because the product formed has less volume than reactant. Pressure : 1 to 2 atmosphere.
Excess of oxygen increases the production of sulphur trioxide.

(d) Sulphuric acid is not obtained by directly reacting SO₃ with water since sulphur trioxide does not dissolve in water satisfactorily and it gives a lot of heat and forms misty droplets of sulphuric acid.

(e) The chemical used to dissolve SO₃ is concentrated sulphuric acid and the product formed is oleum.

Main reactions of this process are:

SO₃ + H₂SO₄ (conc.) ⟶ H₂S₂O₇ (oleum)

H₂S₂O₇ + H₂O ⟶ 2H₂SO₄

Question 3

Why the impurity of arsenic oxide must be removed before passing the mixture of SO₂ and air through the catalytic chamber?

Intext Questions

Answer:

Impurity of arsenic oxide must be removed before passing the mixture of SO₂ and air through the catalytic chamber otherwise the catalyst loses it's efficiency.

Question 4

Name the catalyst which helps in the conversion of sulphur dioxide to sulphur trioxide in step C. In the Contact process for the manufacture of sulphuric acid, sulphur trioxide is not converted to sulphuric acid by reacting it with water. Instead a two steps procedure is used. Write the equations for the two steps involved in D. What type of substance will liberate sulphur dioxide from sodium sulphite in step E? Write the equation for the reaction by which sulphur dioxide is converted to sodium sulphite in step F. Sulphuric Acid, Concise Chemistry Solutions ICSE Class 10

(a) Name the catalyst which helps in the conversion of sulphur dioxide to sulphur trioxide in step C.

(b) In the Contact process for the manufacture of sulphuric acid, sulphur trioxide is not converted to sulphuric acid by reacting it with water. Instead a two steps procedure is used. Write the equations for the two steps involved in D.

(d) Write the equation for the reaction by which sulphur dioxide is converted to sodium sulphite in step F.

Intext Questions

Answer:

(a) Vanadium pentoxide

$2\text{SO}_2 + \text{O}_2 \xrightleftharpoons [450-500\text{\degree C }/1 - 2 \text{ atmos}]{\text{V}_2\text{O}_5} 2\text{SO}_3 + \text{45 K cals}$

(b) Main reactions of this process are:

SO₃ + H₂SO₄ (conc.) ⟶ H₂S₂O₇ (oleum)

H₂S₂O₇ + H₂O ⟶ 2H₂SO₄

Na₂SO₃ + H₂SO₄ ⟶ Na₂SO₄ + H₂O + SO₂[g] ↑

(d) 2NaOH + SO₂ ⟶ Na₂SO₃ + H₂O