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Analysis of Potassium Phosphate (K₃PO₄)

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: White
  • Odour: Odourless
  • State: Crystalline solid
  • Solubility: Soluble 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 (K⁺)

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⁺ as the cation (basic radical) and PO₄³⁻ as the anion (acidic radical). The salt is Potassium Phosphate (K₃PO₄).

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.