Acids, Bases and Salts — Question 14

(a) Chlorides do not react with dilute acids. They react with concentrated sulphuric acid on warming to liberate hydrogen chloride.

$\text{NaCl} + \text{H}_2\text{SO}_4 [\text{conc.}] \xrightarrow{\lt 200 \degree\text{C}}\text{NaHSO}_4 + \text{HCl}$

$2\text{NaCl} + \text{H}_2\text{SO}_4 [\text{conc.}] \xrightarrow{\gt 200 \degree\text{C}}\text{Na}_2\text{SO}_4 + 2\text{HCl}$

(b) Nitrates do not react with dilute acids. When heated with conc. sulphuric acid they produce more volatile nitric acid.

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

$2\text{KNO}_3 + \text{H}_2\text{SO}_4 [\text{conc.}] \xrightarrow{\gt 200 \degree\text{C}}\text{K}_2\text{SO}_4 + 2\text{HNO}_3$