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Experiment No. N

Analysis of Manganese(II) Sulphite (MnSO₃)

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
Warm 1 mL of water extract or sodium carbonate extract with dilute H₂SO₄Colourless gas with pungent smell of burning sulphur is evolvedSO₃²⁻ may be present
Confirmatory Tests
Barium Chloride Test
Add barium chloride to water extract or sodium carbonate extract		White precipitate dissolves on adding dilute HCl and SO₂ is evolvedSO₃²⁻ is confirmed
KMnO₄ Decolourisation Test
Add dilute H₂SO₄ to the barium sulphite precipitate and then very dilute KMnO₄ solution		Colour of potassium permanganate solution is dischargedSO₃²⁻ is confirmed

Test of Cation

ExperimentObservationInference
Original solution + H₂S gas in presence of NH₄OHBlack or flesh-coloured precipitate is formedGroup IV cation may be present
Confirmatory Test
Sodium Hydroxide Test
Dissolve the precipitate in dilute HCl by boiling and add NaOH in excess		White precipitate forms first, then turns brown on standingPresence of Mn²⁺ is confirmed

Result

The given salt contains Mn²⁺ ions as cation and SO₃²⁻ ions as anion. The salt is MnSO₃.

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.