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Experiment No. N

Analysis of Ammonium Bromide (NH₄Br)

Aim

To determine the presence of anion and cation in the given salt

Preliminary Test

  • Odor: Odorless
  • Texture: Crystalline
  • Color: White
  • Solubility: Soluble in water

Test of Anion

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

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⁺ ions as cation and Br⁻ ions as anion. The salt is 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.