Which of the following reactions is used as a confirmatory test for the presence of chloride ions?

JAMB Chemistry 2023 60 views

Which of the following reactions is used as a confirmatory test for the presence of chloride ions?

  1. Formation of a white precipitate with silver nitrate solution ✓
  2. Formation of a blue precipitate with ammonium hydroxide
  3. Liberation of hydrogen gas with zinc metal
  4. Formation of a yellow precipitate with lead(II) nitrate solution

Explanation

When silver nitrate solution is added to a solution containing chloride ions, a white precipitate of silver chloride forms immediately. This cloudiness confirms chloride ions are present.

The chemical equation is: Ag⁺ + Cl⁻ → AgCl. Silver chloride is insoluble in water, causing it to precipitate as a white solid.

This test is specific for chloride ions. The white precipitate is light-sensitive and darkens when exposed to sunlight, further confirming it is silver chloride.

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