Question

Sulphuric acid is manufactured by a contact process.
(c) Why is $H_{2}S{O}_4$ not obtained by directly reacting $S{O}_3$ with water?

Answer 1

• Directly dissolving sulphur trioxide ($S{O}_3$ ) in water is impractical and not possible due to the highly exothermic nature of the reaction.
• The reaction gives acidic vapours or mists and the formation of the fog of sulphuric acid takes place which is difficult to condense instead of a liquid.
• Thus, the reaction between water and sulphur trioxide ($S{O}_3$) forms a ‘mist’ of sulphuric acid which can be difficult to store and handle.
• So, $H_{2}S{O}_4$ is not obtained by directly reacting $S{O}_3$ with water.