Distinguish between the following pairs of compounds using a reagent

Acids, Bases, Salts (10)

Distinguish between the following pairs of compounds using a reagent as a chemical test:

  1. Calcium nitrate and Zinc nitrate solution.
  2. Ammonium sulphate crystals and Sodium sulphate crystals.
  3. Magnesium chloride and Magnesium nitrate solution.

Answer

(i) Add NaOH / KOH / dil H2SO4 to both the solutions

Calcium nitrate forms a white precipitate which is insoluble in excess of NaOH while Zinc nitrate forms a gelatinous white precipitate soluble in excess.

With (dilute) Sulphuric acid ... Calcium nitrate forms a white precipitate while Zinc nitrate does not form precipitate

Or

With NH4OH - Calcium nitrate no reaction or no precipitate while with Zinc nitrate it forms a (gelatinous white) precipitate soluble in excess / or white gelatinous precipitate with zinc nitrate

(ii) Add any alkali / base

Ammonium sulphate produces a pungent colourless gas or colourless gas is released which turns red litmus blue. While there is no reaction with sodium sulphate. Or no
pungent gas released

(iii) Add silver nitrate / lead nitrate solution to both / or perform brown ring test for nitrates

Magnesiumchloride forms a white precipitate while there is no reaction with magnesium nitrate.

Or

Magnesium chloride does not form brown ring with Brown ring test while magnesium nitrate forms a brown ring

  • Exam Year: 2020