Question

Define solubility. Give the main steps with the calculations involved of the method to determine the solubility of a given salt ‘X’ in water.

Answer 1

Solubility: “The maximum amount of a SOLUTE which can be dissolved in 100 grams of a solvent at a specified temperature is called Solubility.
To Determine The Solubility Of ‘X’ In Water :
Steps :
(i) Preparation of saturated solution of ‘X’

1. Take 100 ml of distilled water in a boiling test tube.
2. Add crystals of ‘X’ to distilled water and stir slowly.
3. Continue adding and stirring till the crystals dissolve. Repeat the process until no more salt can dissolve.
4. Pour the saturated solution — in a clean dry test-tube.

Steps :
(ii) Calculations To Determine Solubility Of Solute :

1. Weigh a clean and dry vaporating dish = M₁g
2. Add above saturated solution to it and weigh = M₂g
   ∴ Weight of solution (solute + solvent water) = (M₂ – M₁) g
3. Heat the solution to dryness and weigh the dish with residue = M₃g
   Weight of solute = (M₃ – M₁) g
   weight of solvent (water) = M₂ – M₃ = solution – solute (M₂ – M₁) = (M₃ – M₁) = M₂ – M₁ – M₃ + M₁
4. Note the temperature of saturated solution = t° C.

Solubility = `"weight of solute"/"weight of solvent" xx 100`

`= (("M"_3 - "M"_1)"g")/(("M"_2 - "M"_3)"g") xx 100` at t°C