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 |
|---|---|---|
| Add conc. H₂SO₄ to the solution and boil with a few copper turnings/chips | On heating, brown fumes (NO₂) are evolved in excess and the solution becomes blue | NO₃⁻ may be present |
| Confirmatory Test | ||
| Brown Ring Test Take 1 mL of salt solution, add 2 mL conc. H₂SO₄, cool, then add freshly prepared ferrous sulphate solution along the sides | Brown ring is formed at the junction of the two solutions | NO₃⁻ is confirmed |
| Experiment | Observation | Inference |
|---|---|---|
| Original solution + H₂S gas in presence of dil. HCl | Black precipitate of Group-II A is formed | Group-II cation may be present |
| Confirmatory Tests | ||
| Ammonium Hydroxide Test To the original solution (or the filtrate after dissolving the black ppt in dilute HNO₃) add NH₄OH dropwise, then in excess | Pale blue precipitate of Cu(OH)₂ dissolves in excess NH₄OH giving a deep blue tetraamminecopper(II) solution | Cu²⁺ is confirmed |
| Potassium Ferrocyanide Test Acidify the solution with acetic acid and add potassium ferrocyanide | Chocolate-brown precipitate of copper ferrocyanide | Presence of Cu²⁺ is confirmed |
The given salt contains Cu²⁺ as the cation (basic radical) and NO₃⁻ as the anion (acidic radical). The salt is Copper(II) Nitrate (Cu(NO₃)₂).