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Analysis of Ammonium Bromide (NH₄Br)

Qualitative analysis

Aim

To analyse the given inorganic salt for one acidic and one basic radical.

Preliminary Test

  • Colour: White
  • Odour: Ammoniacal
  • State: Crystalline solid
  • Solubility: Soluble in water

Test of Anion (Br⁻)

ExperimentObservationInference
Take 0.1 g of salt in a test tube and add conc. H₂SO₄ (or add MnO₂ if needed) and warmReddish brown fumes of bromine are evolvedBr⁻ may be present
Confirmatory Tests
Layer Test
Take 1 mL of neutralized extract, add CCl₄/CHCl₃ (or other suitable organic solvent), then add chlorine water dropwise and shake vigorously
Orange-brown colouration appears in the organic layerBr⁻ is confirmed
Silver Nitrate Test
Acidify sodium carbonate extract with dilute HNO₃ (or use water extract) and add AgNO₃
Pale yellow precipitateBr⁻ is confirmed

Test of Cation (NH₄⁺)

ExperimentObservationInference
Take 0.1 g of salt and add 1–2 mL of NaOH solution, then heatA smell of ammonia is evolvedNH₄⁺ may be present
Bring a glass rod dipped in hydrochloric acid near the mouth of the test tubeDense white fumes are observedNH₄⁺ may be present
Confirmatory Test
Nessler's Reagent Test
Pass the evolved gas through Nessler’s reagent
Brown colouration or a brown precipitate of basic mercury(II) amido-iodide is obtainedPresence of NH₄⁺ is confirmed

Result

The given salt contains NH₄⁺ as the cation (basic radical) and Br⁻ as the anion (acidic radical). The salt is Ammonium Bromide (NH₄Br).

Precautions

  1. Handle the chemicals with care.
  2. Don't use excess of chemicals.
  3. Keep the mouth of the test tube away from the face.