Question

1) 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?
2) You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dilute HCl, dilute HNO3, ZnCl2 and H2O. In which of the above containers these solutions can be kept?

Answer 1

a) BaCl2 + Na2SO3 ——-> BaSO3 +.
2NaCl
b) double displacement reaction
c) the white precipitate is barium sulphite which on reacting with HCl form barium chloride and water and barium chloride dissolves in the water
REACTION :
BaSO3 +2 HCl ——> BaCl2 + H2O +
SO2

2) in copper as it is less reactive than aluminum and comes after hydrogen and zinc in reactivity series so it won’t react with them or displace them.