Question

(a) in Contact process, sulphur dioxide can be oxidised to sulphur trioxide in the presence of platinised asbestos which acts as a catalyst. The reaction is exothermic. Explain what is meant by the terms in Italics.
(b) Give examples of the use of sulphuric acid.
(i) As an electrolyte In everyday use.
(ii) As non-volatile acid.
(iii) As an oxidising agent.
[5 MARKS]

Answer 1

Option a: 2 Marks
Option b: 3 Marks

(a) Oxidised : A substanoe is said to be oxidised if oxygen or any electronegative element or radical is added to it. In contact process sulphur dioxide $\left(S{O}_2\right)$ changes to sulphur trioxide $\left(S{O}_3\right)$ i.e., oxygen is added. Therefore, it is said to be oxidised.
Catalyst : A substance which generally increases the rate of a chemical reaction without undergoing any change and can be recovered as such at the completion of the reaction is called a catalyst. Here platinised asbestos acts as a catalyst in the oxidation of $S{O}_2$ to $S{O}_3$.
Exothermic : A reaction is said to be exothermic if heat is evolved in it.
(b) (i) Use of sulphuric acid in storage batteries.
(ii) Use of sulphuric acid in the preparation of hydrochloric acid, nitric acid and acetic acid.
(iii) Use of sulphuric acid in the preparation of sulphur dioxide.