Notebook Theme

Analysis of Arsenic(III) Acetate (As(CH₃COO)₃)

Qualitative analysis

Aim

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

Preliminary Test

  • Colour: White
  • Odour: Vinegar-like
  • State: Crystalline solid
  • Solubility: Soluble in water

Test of Anion (CH₃COO⁻)

ExperimentObservationInference
Take 0.1 g salt + dilute H₂SO₄Colourless vapours with vinegar-like smell evolveCH₃COO⁻ may be present
Confirmatory Tests
Ester Test
Take 0.1 g salt in a test tube with ethanol and a little conc. H₂SO₄, then heat
Fruity odour of ethyl acetate is developedCH₃COO⁻ is confirmed
Ferric Chloride Test
Add neutral ferric chloride solution to the salt solution
Deep red colour appears; on heating it disappears and a brown-red precipitate formsCH₃COO⁻ is confirmed

Test of Cation (As³⁺)

ExperimentObservationInference
Original solution + H₂S gas in presence of dil. HCl and NH₄ClYellow precipitate is formedGroup-II-B (As³⁺) may be present
Confirmatory Test
Ammonium Molybdate Test
Treat the dissolved precipitate with concentrated nitric acid and ammonium molybdate solution
Canary yellow precipitate is formedPresence of As³⁺ is confirmed

Result

The given salt contains As³⁺ as the cation (basic radical) and CH₃COO⁻ as the anion (acidic radical). The salt is Arsenic(III) Acetate (As(CH₃COO)₃).

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.