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 |
|---|---|---|
| Take 0.1 g of salt in a test tube and add conc. H₂SO₄ | Deep violet vapour with a pungent odour is evolved | I⁻ may be present |
| Confirmatory Tests | ||
| Layer Test Take test solution or extract, add CHCl₃/CCl₄ and chlorine water dropwise, then shake vigorously | Violet colouration appears in the organic layer | I⁻ is confirmed |
| Silver Nitrate Test Acidify sodium carbonate extract with dilute HNO₃ and add AgNO₃ | Yellow precipitate is obtained, insoluble in excess NH₄OH | I⁻ is confirmed |
| Experiment | Observation | Inference |
|---|---|---|
| Original solution + H₂S gas in presence of NH₄OH | Black precipitate is formed | Group IV cation may be present |
| Dissolve the black sulphide precipitate in aqua regia and heat | Residue remains in solution after evaporation | Co²⁺ may be present |
| Confirmatory Test | ||
| Potassium Hexanitritocobaltate(III) Test Neutralise with NH₄OH, acidify with dilute acetic acid and add strong potassium nitrite solution | Yellow precipitate is formed | Presence of Co²⁺ is confirmed |
The given salt contains Co²⁺ as the cation (basic radical) and I⁻ as the anion (acidic radical). The salt is Cobalt(II) Iodide (CoI₂).