Question

Potassium nitrate + sulphuric acid $⟶$ Potassium bisulphate + nitric acid. This reaction takes place at:

• A. less than ${200}^{\circ }C$
• B. more than ${200}^{\circ }C$
• C. ${200}^{\circ }C$
• D. None of the above

Answer 1

The correct option is A less than ${200}^{\circ }C$

$KN{O}_3$$+$$H_{2}S{O}_4$$\to$$KHS{O}_4$$+$$HN{O}_3$

This reaction is used mainly for the preparation of nitric acid.

The reaction takes place at less than ${200}^{\circ }C$ because above this temperature, nitric acid decomposes to nitrogen dioxide.

Moreover, at a higher temperature, $KHS{O}_4$, that is potassium bisulfate gets converted to $K_{2}S{O}_4$, that is potassium sulfate. This $K_{2}S{O}_4$ reacts with the glass tube in which the reaction is occurring and renders the glass tube useless.

Thus, the temperature should be maintained below ${200}^{\circ }C$.

Hence, option A is correct.