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 |
|---|---|---|
| Confirmatory Tests | ||
| If Group V is absent, add disodium hydrogen phosphate solution and scratch the inner walls with a glass rod | A white crystalline precipitate of magnesium ammonium phosphate is formed | Mg²⁺ may be present |
| Magneson Test To the alkaline solution add a drop of Magneson I reagent (p-nitrobenzeneazoresorcinol) | A blue precipitate / blue lake is formed | Mg²⁺ is confirmed |
The given salt contains Mg²⁺ as the cation (basic radical) and S²⁻ as the anion (acidic radical). The salt is Magnesium Sulphide (MgS).