SELINA Solutions for Class 10 Chemistry Chapter 11 - Study of Compounds D. Sulphuric Acid
Chapter 11 - Study of Compounds D. Sulphuric Acid Exercise Intext 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.
(a) Two balanced equations to obtain SO2 is:
(i) 4FeS2 + 11O2 2Fe2O3 +8SO2
(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 4100C-450oC
(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) Vanadium pentoxide (V2O5)
(d) 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.
(e)The chemical used to dissolve SO3 is concentrated sulphuric acid. The product formed is oleum.
(f) Hydrogen sulphide.
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.
(a) The catalyst which helps in the conversion of sulphur dioxide to sulphur trioxide in step C is Vanadium pentoxide.
(b) The two steps for the conversion of sulphur trioxide to sulphuric acid is:
(i) SO3 + H2SO4H2S2O7
(ii) H2S2O7 + H2O 2H2SO4
(c)The substance that will liberate sulphur dioxide in step E is dilute H2SO4.
(d) The equation for the reaction by which sulphur dioxide is converted to sodium sulphite in step F is:
Chapter 11 - Study of Compounds D. Sulphuric Acid Exercise Ex. 11
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.
Balanced reactions are:
(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.
(b) Oxidising agent:
H2SO4 H2O +SO2 +[O]
Nascent oxygen oxidizes non-metals, metals and inorganic compounds.
Carbon to carbon dioxide
C+H2SO4 CO2 +H2O +2SO2
Sulphur to sulphur dioxide
S +H2SO4 3SO2 +2H2O
(d) Non-volatile nature:
It has a high boiling point (356oC) 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 + H2SO4NaHSO4 +HCl
KCl + H2SO4 KHSO4 +HCl
(a)Bring a glass rod dipped in Ammonia solution near the mouth of each test tubes containing dil. Hel and dil. H2SO4each.
White fumes of ammonium chloride
No such fumes
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.
(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 H22O1112C + 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
(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.
(c) Concentrated sulphuric acid has high boiling point (356oC). 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.
NaNO3 +H2SO4NaHSO4 +HNO3
(a) Due to its reducing property. i.e, it is a non-volatile acid.
NaCl+ H2SO4NaHSO4 + HCl
(b) It is a dehydrating agent.
HCOOH 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
The name of the salt of
(a) Hydrogen sulphites and Sulphites.
(b) Sulphate and bisulphate.
(a) Two types of salts are formed when sulphuric acid reacts with NaOH because sulphuric acid is dibasic.
NaOH + H2SO4 NaHSO4 + H2O
2NaOH + H2SO4Na2SO4 + 2H2O
(b) When hydrogen bromide reacts with sulphuric acid the bromine gas is obtained which produce red brown vapours.
2KBr+3H2SO4 2KHSO4+SO2+Br2 +2H2O
(c) A piece of wood becomes black when concentrated sulphuric acid is poured on it because it gives a mass of carbon.
(d) When sulphuric acid is added to sodium carbonate it liberates carbon dioxide which produces brisk effervescence.
Substance reacted with acid
Dilute or concentrated acid
Substance reacted with acid
Dilute or concentrated sulphuric acid
Dilute sulphuric acid
Concentrated sulphuric acid
Bleaching power CaOCl2
Dilute sulphuric acid
(i) Active metal + Acid ⟶ Metal sulphate + Hydrogen
(ii) Base + Acid ⟶ Salt + Water
(iii) Carbonate/hydrogen carbonate + Acid ⟶ Salt + Water + Carbon dioxide
(iv) Sulphite/hydrogen sulphite + Acid ⟶ Salt + Water + Sulphur dioxide
(v) Sulphite + Acid ⟶ Salt + Hydrogen sulphide
Sulphuric acid is powerful dehydrating agent on account of its strong affinity towards water.
Concentrated sulphuric acid as
i. Oxidising agent:
The oxidising property of conc. sulphuric acid its due to the fact that on thermal decomposition, it yeilds nacent oxygen [O].
H2SO4→ H2O + SO2 + [O]
ii. Non-volatile acid:
conc. sulphuric acid has high boiling point (338°C) that why it is said to be a non volitile compound, therefore it is used for preparing volatile acids like hydrochloric acids, nitric acids from there salts by double decomposition
H2SO4 + NaCl → NaHSO4 + HCl
(a) The acid formed when sulphur dioxide dissolves in water is sulphurous acid.
(b) Carbondioxide gas is released when sodium carbonate is added to solution of sulphur dioxide.
a. (C) Lead nitrate
b. Liquid E is Ethanol.
Name of process
Equation for catalyzed reaction output
Sulphur dioxide + oxygen
Platinum or V2O5
2SO2 + O2 ⇄ 2SO3
i. Zn + dil. H2SO4→ ZnSO4 + H2
ii. Na2CO3 + dil. H2SO4→ Na2SO4 + H2O + CO2
iii. Pb(NO3) + dil. H2SO4→ PbSO4 + 2HNO3
iv. Zn + dil. H2SO4→ ZnSO4 + H2
ZnSO4 + Na2CO3→ ZnCO3 + Na2SO4
i. The property of concentrated sulphuric acid which allows it to be used in is used in the action when sugar turns black in its presence is its dehydrating property.
ii. The property of concentrated sulphuric acid which allows it to be used in the preparation of hydrogen chloride and nitric acid is its non-volatility.
H2SO4 + BaCl2 → BaSO4 + 2HCl
i. S + H2SO4 → 3SO2 +2H2O.
ii. C12H22O11 + Conc. H2SO4 → 6C + 6H2O
b. ZnO + H2SO4 → ZnSO4 + H2O.
c. C) Dilute sulphuric acid.
a. Charring of sugar takes place. Sulphuric acid dehydrates sugar leaving behind carbon which is black in colour.
b. i. Hydrogen sulphide
i. Non-volatile nature
ii. as an oxidising agent
a. Hydrogen Sulphide (H2S).
i. (B) Dehydrating agent
ii. (D) Oxidising agent
iii. (C) Non-volatile acid
iv. (A) Dilute acid
v. (D) Oxidising agent
c. ZnS + dil.H2SO4→ ZnSO4 + H2S
a. when Conc. H2SO4 is added to a crystal of hydrated copper sulphate,it removes water of crystalisation from salt.
b. ii. Oxidising agent
c. C12H22O11 + Conc. H2SO4 → 6C + 6H2O
d. Sulphuric acid (H2SO4)
a. C + H2SO4 → CO2 + 2H2O + 2SO2.
b. Sulphuric acid precipitates the insoluble sulphate of barium from the solution of barium chloride.
BaCl2 + H2SO4→ BaSO4 + 2HCl
Dilute HCl does not react with barium chloride solution, and thus, no precipitate is produced in the reaction.
c. Two conditions for the conversion of sulphur dioxide to sulphur trioxide is as follows:
Temperature: 450-500° C Catalyst: V2O5
i. Dehydrating property of sulphuric acid:
H2SO4 has a great affinity for water, and therefore, it acts as a dehydrating agent.
ii. Acidic nature of sulphuric acid:
It acts as a strong dibasic acid.
H2SO4→ 2Hi+ + SO42-
It reacts with metals, metal oxides, metal hydroxides, carbonates etc. to form metallic sulphates and hydrogen at ordinary temperature.
Mg + H2SO4→ MgSO4 + H2↑
CuO + H2SO4→ CuSO4 + H2O
2NaOH + H2SO4→ Na2SO4 + 2H2O
ZnCO3 + H2SO4→ ZnSO4 + H2O + CO2↑
iii. As a non-volatile acid:
It has a high boiling point, so it is used to prepare volatile acids such as HCl, HNO3 and acetic acid from their salts.
NaCl + H2SO4→ NaHSO4 + HCl
NaNO3 + H2SO4→ NaHSO4 + HNO3
CH3COONa + H2SO4→ NaHSO4 + CH3COOH
(a) In the contact process for the manufacture of sulphuric acid, the equations for the conversion of sulphur trioxide to sulphuric acid are
SO3 + H2SO4 → H2S2O7
(oleum or pyrosulphuric acid)
H2S2O7 + H2O → 2H2SO4
(i) Action of sulphuric acid on potassium hydrogen carbonate
2KHCO3+ H2SO4→ K2SO4+ 2H2O + 2CO2↑
(ii) Action of sulphuric acid on sulphur
S + 2H2SO4→ 3SO2 + 2H2O
(i) Concentrated sulphuric acid
(ii) Concentrated sulphuric acid
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