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 |
|---|---|---|
| Warm the solid salt with dilute H₂SO₄ | Brown fumes of NO₂ are evolved | NO₂⁻ may be present |
| Confirmatory Tests | ||
| Potassium Iodide Starch Test Take evolved gas and add KI + starch solution acidified with acetic acid | Blue colour appears | NO₂⁻ is confirmed |
| Sulphanilic Acid / 1-Naphthylamine Test Acidify 1 mL of water extract with acetic acid and add sulphanilic acid solution followed by 1-naphthylamine reagent | Red colour is formed | NO₂⁻ is confirmed |
| Experiment | Observation | Inference |
|---|---|---|
| Original solution + Dilute HCl | White precipitate | Pb²⁺ may be present |
| Confirmatory Tests | ||
| Potassium Iodide Test Dissolve one part of the hot precipitate in hot water and add potassium iodide solution | Yellow precipitate is formed | Presence of Pb²⁺ is confirmed |
| Potassium Chromate Test To the acidified solution obtained above, add potassium chromate solution | Yellow precipitate is formed | Presence of Pb²⁺ is confirmed |
| Lead Sulphate Test Dissolve lead sulphide precipitate in dilute HNO₃, then add a few drops of dilute H₂SO₄ and alcohol | White precipitate of lead sulphate is formed | Presence of Pb²⁺ is confirmed |
The given salt contains Pb²⁺ as the cation (basic radical) and NO₂⁻ as the anion (acidic radical). The salt is Lead(II) Nitrite (Pb(NO₂)₂).