Question

Name the acid formed when sulphur dioxide dissolves in water.

Answer 1

Hint: We know that sulphur is present in the group $16$ of the modern periodic table and it is considered as a non-metal. As the non-metal oxides are acidic in nature, sulphur dioxide is also acidic in nature. When it combines with water (or dissolves in water) it will produce an acid which we will see in the solution through the chemical equation which is involved during the reaction between them.

Complete answer:
As we know that sulphur is present in the group $16$ of the modern periodic table and it is considered as a non-metal. Non-metal oxides are generally acidic in nature and hence, the sulphur dioxide is also acidic in nature. Therefore, when the sulphur dioxide is dissolved in water, an acid is produced.
Sulphur dioxide has chemical formula as $S{O_2}$ and the chemical formula of water is ${H_2}O.$
Sulphur reacts with oxygen molecule to form sulphur dioxide as follows:
$S + {O_2} \to S{O_2}$
Therefore, when the sulphur is burned in presence of oxygen, it produces sulphur dioxide and some trace amount of sulphur trioxide whose chemical formula is $S{O_3}$ .
The reaction of sulphur dioxide and water is given as follows:
$S{O_2}(g) + {H_2}O \to {H_2}S{O_3}(aq)$
Therefore, sulphurous acid $({H_2}S{O_3})$ is formed when sulphur dioxide dissolves in water.

Note:
Sulphurous acid is a colorless liquid and it is an oxyacid of sulphur. When it is burned in air, it burns with a pungent smell because it contains sulphur atoms. It is very unstable in nature and hence, cannot be obtained in its pure form. Sulphur dioxide is used for refining of sugars and in the petroleum industries.