On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, white precipitate is obtained.

(a) Write a balanced chemical equation of the reaction involved

(b) What other name can be given to this precipitation reaction?

(c) On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?

(a) When Barium chloride solution is added to an aqueous solution of sodium sulphite, we obtain a white precipitate of Barium Sulphite along with Sodium Chloride.
BaCl₂ + Na₂SO₃→ BaSO₃ + 2NaCl

(b) This precipitation reaction can also be categorised as a double displacement reaction.

A double displacement reaction is a type of chemical reaction in which two chemical compounds react and the positive ions(cations) and the negative ions(anions) of the two compounds switch places.

(c) The white precipitate of sodium chloride reacts with hydrochloric acid to form Barium Chloride and water and release sulphur dioxide. Barium chloride is a soluble salt which is why the white precipitate of Barium Sulphite disappears.

The chemical reaction for the above process is BaSO₃ + HCl ⇨ BaCl₃ + SO₂ + H₂O.