Question

Pragya tested the solubility of potassium chloride at different temperatures and collected the data as given below (results are given in the following table, as grams of substance dissolved in 100 grams of water to form a saturated solution).

She makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools? Explain.

Answer 1

• At 353 K, 100 g water can dissolve a maximum of 54 g potassium chloride. When the saturated solution of potassium chloride at 353 K is allowed to cool down at room temperature (say 293 K), the excess potassium chloride dissolved in the solution at that temperature gets separated out from the solution by forming crystals. ​

• Therefore, Pragya would observe the crystals of potassium chloride as the solution cools down.​