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, add 1–2 mL of dilute H₂SO₄ | Colourless odourless gas is evolved with brisk effervescence; lime water turns milky | CO₃²⁻ may be present |
| Confirmatory Test | ||
| Lime Water Test Pass the gas through lime water | Lime water turns milky; milkiness disappears on passing excess gas (soluble calcium bicarbonate) | CO₃²⁻ 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 CO₃²⁻ as the anion (acidic radical). The salt is Cobalt(II) Carbonate (CoCO₃).