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Experiment No. N

Analysis of Potassium Bromide (KBr)

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
Flame test in a clean non-luminous flameLilac flameK⁺ may be present
Confirmatory Test
Sodium Cobaltinitrite Test
Salt solution + sodium cobaltinitrite reagent
Yellow precipitateK⁺ is confirmed

Result

The given salt contains K⁺ ions as cation and Br⁻ ions as anion. The salt is KBr.

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.