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 |
|---|---|---|
| Universal Indicator | Solution turns blue or purple | OH⁻ may be present |
| Confirmatory Test | ||
| Phenolphthalein Test Add phenolphthalein indicator to salt solution | Solution turns pink | OH⁻ is confirmed |
| Experiment | Observation | Inference |
|---|---|---|
| Confirmatory Tests | ||
| If Group V is absent, add disodium hydrogen phosphate solution and scratch the inner walls with a glass rod | A white crystalline precipitate of magnesium ammonium phosphate is formed | Mg²⁺ may be present |
| Magneson Test To the alkaline solution add a drop of Magneson I reagent (p-nitrobenzeneazoresorcinol) | A blue precipitate / blue lake is formed | Mg²⁺ is confirmed |
The given salt contains Mg²⁺ as the cation (basic radical) and OH⁻ as the anion (acidic radical). The salt is Magnesium Hydroxide (Mg(OH)₂).