To determine the presence of anion and cation in the given salt
| 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 Tests | ||
| Lime Water Test Pass the gas through lime water | Lime water turns milky; milkiness disappears on excess gas | CO₃²⁻ is confirmed |
| Sodium Nitroprusside Test Take 1 mL water extract or sodium carbonate extract, make it alkaline with dilute NH₄OH, then add a drop of sodium nitroprusside | Purple or violet colouration is produced | CO₃²⁻ is confirmed |
| Experiment | Observation | Inference |
|---|---|---|
| Original solution + Dil. HCl + NH₄Cl solid + NH₄OH | White gelatinous precipitate | Al³⁺ may be present |
| Confirmatory Tests | ||
| Dissolve white precipitate in dilute HCl and divide into two parts | To the first part, add sodium hydroxide and warm. A white gelatinous precipitate dissolves in excess sodium hydroxide solution | Aluminium is confirmed |
| Blue Lake Test To the second part, add few drops of blue litmus solution and then NH₄OH dropwise along the sides of the test tube | A blue floating mass appears in colourless solution | Presence of Al³⁺ is confirmed |
The given salt contains Al³⁺ ions as cation and CO₃²⁻ ions as anion. The salt is (Al)₂(CO₃)₃.