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Analysis of Manganese(II) Phosphate (Mn₃(PO₄)₂)

Qualitative analysis

How to do salt analysis · Viva · Quiz

Aim

To analyse the given inorganic salt for one acidic and one basic radical.

Preliminary Test

  • Colour: Pale pink
  • Odour: Odourless
  • State: Crystalline solid
  • Solubility: Insoluble in water

Test of Anion (PO₄³⁻)

ExperimentObservationInference
Confirmatory Test
Ammonium Molybdate Test
Acidify with conc. HNO₃ and add ammonium molybdate solution, boil		Canary yellow precipitate is formedPO₄³⁻ is confirmed

Test of Cation (Mn²⁺)

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⁺ as the cation (basic radical) and PO₄³⁻ as the anion (acidic radical). The salt is Manganese(II) Phosphate (Mn₃(PO₄)₂).

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.