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 | Black precipitate of Group-II A is formed | Group-II cation may be present |
| Confirmatory Tests | ||
| Ammonium Hydroxide Test To the original solution (or the filtrate after dissolving the black ppt in dilute HNO₃) add NH₄OH dropwise, then in excess | Pale blue precipitate of Cu(OH)₂ dissolves in excess NH₄OH giving a deep blue tetraamminecopper(II) solution | Cu²⁺ is confirmed |
| Potassium Ferrocyanide Test Acidify the solution with acetic acid and add potassium ferrocyanide | Chocolate-brown precipitate of copper ferrocyanide | Presence of Cu²⁺ is confirmed |
The given salt contains Cu²⁺ as the cation (basic radical) and SO₃²⁻ as the anion (acidic radical). The salt is Copper(II) Sulphite (CuSO₃).