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 the salt with dilute H₂SO₄ | Colourless gas with smell of rotten eggs is evolved | S²⁻ may be present |
| Confirmatory Tests | ||
| Lead Acetate Test Pass gas through filter paper dipped in lead acetate solution | Paper turns black | S²⁻ is confirmed |
| Sodium Nitroprusside Test Make solution alkaline with NH₄OH (or sodium carbonate extract) and add sodium nitroprusside solution | Purple/violet colouration is produced | S²⁻ is confirmed |
| Experiment | Observation | Inference |
|---|---|---|
| Original solution + H₂S gas in presence of NH₄OH | White precipitate is formed | Group IV cation may be present |
| Confirmatory Tests | ||
| Sodium Hydroxide Test Add sodium hydroxide solution dropwise | White precipitate forms and dissolves in excess NaOH on heating | Zn²⁺ is confirmed |
| Potassium Ferrocyanide Test After neutralisation with NH₄OH, add potassium ferrocyanide solution | Bluish-white precipitate | Zn²⁺ is confirmed |
The given salt contains Zn²⁺ as the cation (basic radical) and S²⁻ as the anion (acidic radical). The salt is Zinc Sulphide (ZnS).