Prepare the ash solution of the given food and carry out qualitative tests for minerals.

1. 1 · Aim. To prepare the ash solution of the given food and test it for calcium, magnesium, iron, phosphate, chloride and sulphate.
2. 2 · Principle. Ashing at 550-600 °C removes the organic matter; the minerals left in the ash dissolve in dilute acid as ions. Each ion gives a specific precipitate or colour with its own reagent.
3. 3 · Requirements.
   • Silica crucible, muffle furnace, desiccator, water bath, test tubes
   • Dilute HCl and nitric acid, ammonium hydroxide, acetic acid
   • Ammonium oxalate, ammonium molybdate, potassium thiocyanate, potassium ferrocyanide
   • Ammonium chloride, disodium hydrogen phosphate, silver nitrate, barium chloride
4. 4 · Procedure.
   • Char 5-10 g of food, ash at 550-600 °C for 4-6 h, cool in a desiccator.
   • Dissolve the ash in dilute HCl, filter, make up to 100 mL.
   • Use 2 mL portions for each test.
5. 5 · Observation. [Table: Test | Observation | Inference for calcium, magnesium, iron, phosphate, chloride and sulphate, with the exact colours]
6. 6 · Result. The ash solution of the given food contains calcium, magnesium, iron, phosphate, chloride and sulphate (list only those that tested positive).
7. 7 · Precautions.
   • Gloves and goggles; char and use concentrated acids in a fume hood.
   • Never pipette by mouth.
   • Use distilled water and clean glassware to avoid false positives.
   • Warm, do not boil, in the phosphate test.

Scoring tip: The Test | Observation | Inference table with the exact colours earns most of the marks. Name the precipitate in each inference.