Qualitative analysis
How to do salt analysis · Viva · Quiz
To analyse the given inorganic salt for one acidic and one basic radical.
| Experiment | Observation | Inference |
|---|---|---|
| Warm 1 mL of water extract or sodium carbonate extract with dilute H₂SO₄ | Colourless gas with pungent smell of burning sulphur is evolved | SO₃²⁻ 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 evolved | SO₃²⁻ 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 discharged | SO₃²⁻ is confirmed |
| Experiment | Observation | Inference |
|---|---|---|
| Original solution + H₂S gas in presence of dil. HCl and NH₄Cl | Yellow precipitate is formed | Group-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 formed | Presence of As³⁺ is confirmed |
The given salt contains As³⁺ as the cation (basic radical) and SO₃²⁻ as the anion (acidic radical). The salt is Arsenic(III) Sulphite (As₂(SO₃)₃).