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Experiment No. N

Analysis of Potassium Chloride (KCl)

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 and add conc. H₂SO₄A colourless gas is evolved which gives dense white fumes with ammoniaCl⁻ may be present
Confirmatory Tests
Concentrated H₂SO₄ and MnO₂ Test
Take a pinch of MnO₂ in salt solution and add 3–4 drops of conc. H₂SO₄, then heat
Greenish yellow chlorine gas is evolvedPresence of Cl⁻ is indicated
Silver Nitrate Test
Acidify 1 mL of sodium carbonate extract with dilute HNO₃ (or use water extract) and add AgNO₃ solution
Curdy white precipitate soluble in NH₄OHCl⁻ is confirmed
Chromyl Chloride Test
Take a little salt with solid K₂Cr₂O₇, add conc. H₂SO₄, heat. Pass the evolved gas through sodium hydroxide solution, divide into two parts. Acidify one part with acetic acid and add lead acetate solution
The sodium hydroxide solution becomes yellow; adding acetic acid and lead acetate gives yellow precipitate of lead chromateCl⁻ 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 Cl⁻ ions as anion. The salt is KCl.

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.