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Experiment No. N

Analysis of Potassium Iodide (KI)

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. H₂SO₄Deep violet vapour with a pungent odour is evolvedI⁻ may be present
Confirmatory Tests
Layer Test
Take test solution or extract, add CHCl₃/CCl₄ and chlorine water dropwise, then shake vigorously		Violet colouration appears in the organic layerI⁻ is confirmed
Silver Nitrate Test
Acidify sodium carbonate extract with dilute HNO₃ and add AgNO₃		Yellow precipitate is obtained, insoluble in excess NH₄OHI⁻ 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 I⁻ ions as anion. The salt is KI.

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.