To determine the presence of anion and cation in the given salt
| Experiment | Observation | Inference |
|---|---|---|
| Confirmatory Tests | ||
| If no earlier anion test is positive, acidify the extract with dilute HCl and add BaCl₂ solution | White precipitate of barium sulphate, insoluble in conc. HCl or conc. HNO₃ is obtained | SO₄²⁻ may be present |
| Lead Acetate Test Acidify the solution with acetic acid and add lead acetate solution | White precipitate appears | Presence of SO₄²⁻ 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 SO₄²⁻ ions as anion. The salt is (Al)₂(SO₄)₃.