Distinguish between the following pairs of compounds

Analytical Chemistry (10)

Distinguish between the following pairs of compounds using the reagent given in the bracket.

  1. Manganese dioxide and copper (II) oxide. (using concentrated HCl)
  2. Ferrous sulphate solution and ferric sulphate solution. (using sodium hydroxide solution)
  3. Dilute hydrochloric acid and dilute sulphuric acid. (using lead nitrate solution)

Answer

(i) On adding concentrated hydrochloric acid if a greenish yellow gas is evolved it is Manganese dioxide.

If no gas is evolved it is CuO.

(ii) On adding sodium hydroxide solution if a dirty green precipitate is formed it is ferrous sulphate solution.

If a reddish-brown precipitate is formed, it is Ferric sulphate solution.

(iii) On adding lead nitrate solution, if white precipitate is formed which dissolves on heating, then it is dilute HCl.

If white precipitate formed does not dissolve on heating, it is dilute H2SO4.

  • Exam Year: 2019