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 | No reaction | Group I cation is absent |
| Original solution + Dilute HCl + H₂S gas (with NH₄Cl) | No reaction | Group II cation is absent |
| Original solution + Dilute HCl + NH₄Cl solid + NH₄OH | No reaction | Group III cation is absent |
| Original solution + NH₄Cl + NH₄OH + (NH₄)₂CO₃ | White precipitate is formed | Group V cation may be present |
| Confirmatory Tests | ||
| Flame Test Moisten the salt with conc. HCl and introduce it into a non-luminous flame | Crimson-red flame | Sr²⁺ is confirmed |
| Ammonium Sulphate Test Dissolve white precipitate in dilute acetic acid and add ammonium sulphate solution | White precipitate of strontium sulphate | Sr²⁺ is confirmed |
The given salt contains Sr²⁺ as the cation (basic radical) and NO₂⁻ as the anion (acidic radical). The salt is Strontium Nitrite (Sr(NO₂)₂).