Question

On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, white precipitate is obtained.
i. Write a balanced chemical equation of the reaction involved.
ii. What other name can be given to this precipitation reaction?
iii. On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?

Answer 1

ii. This reaction can also be named as double displacement reaction.
iii. On adding dilute hydrochloric acid (HCl) to the reaction mixture, white precipitate disappears because barium sulphite reacts with excess HCl to form barium chloride and sulphur dioxide. Barium chloride is soluble in water

Answer 2

(iii) Due to the formation of BaCl₂​ which is soluble, hence the white ppt. disappears.