Notebook Theme

Analysis of Zinc Phosphate (Zn₃(PO₄)₂)

Qualitative analysis

Aim

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

Preliminary Test

  • Colour: White
  • 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 (Zn²⁺)

ExperimentObservationInference
Original solution + H₂S gas in presence of NH₄OHWhite precipitate is formedGroup IV cation may be present
Confirmatory Tests
Sodium Hydroxide Test
Add sodium hydroxide solution dropwise
White precipitate forms and dissolves in excess NaOH on heatingZn²⁺ is confirmed
Potassium Ferrocyanide Test
After neutralisation with NH₄OH, add potassium ferrocyanide solution
Bluish-white precipitateZn²⁺ is confirmed

Result

The given salt contains Zn²⁺ as the cation (basic radical) and PO₄³⁻ as the anion (acidic radical). The salt is Zinc Phosphate (Zn₃(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.