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

The solubility of a solute in a solvent at a particular temperature is the maximum amount of the solute in grams that will saturate 100 g. of the solvent at that temperature.

Determination of Solubility of 'X' In Water :

Step 1 : Preparation of saturated solution of 'X'

• Take a boiling tube half filled with about 100 ml of distilled water.
• Add crystals of 'X' to distilled water and stir slowly.
• Continue stirring till the crystals dissolve. Repeat the process till no more salt can dissolve.
• Pour the saturated solution — in a clean dry test-tube.

Step 2 :

(ii) Calculations To Determine The Solubility Of Solute :

• Weigh a clean and dry evaporating dish = M g
• Add the above saturated solution to it and reweigh = M₁ g
• Heat the solution to dryness and reweigh the dish with residue = M₂g
• ∴ Weight of solute = (M₂ – M) g
• Note the temperature of saturated solution = t° C

Solubility = $\dfrac{\text{Weight of solute}}{\text{Weight of solvent}}$ x 100

Solubility = $\dfrac{[\text{M}$2 – \text{M]} \text{ g}}{\text{[M}1 - \text{M}_2] \text{ g} } x 100 at t° C