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.
Ans. Balanced chemical equation
NaSO3(aq) + BaCl2(aq) → BaSO3(s) + 2NaCl(aq)
(b) What other name can be given to this precipitation reaction?
Ans. This reaction is also known as double displacement reaction.
(c) On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?
Ans. BaSO3 is a salt of a weak acid (H2SO3) , therefore dilute acid such as HCl decomposes barium sulphite to produce sulphur dioxide gas which has the smell of burning sulphur
BaSO3(s) + HCl → BaCl2 + H2O + SO2(g)
