Chapter 21, Problem 10STP

To determine

The mass of potassium chloride that comes out of the solution when a warm solution containing 100 g of potassium chloride in 200 g of water is cooled to 20 $°C$ .

Answer to Problem 10STP

32 g

Explanation of Solution

Introduction:

Solubility of potassium chloride = 34 g per 100 g of water at 20 $°C$ .

It means 34 g of potassium chloride will dissolve at 20 $°C$ and form the saturated solution. It cannot dissolve more at 20 $°C$ .

A warm solution containing 100 g of potassium chloride in 200 g of water.

So, at 20 $°C$ ; solubility of this solution (warm solution which has been cooled now) is 50 g per 100 g of water.

Since the solution is not supersaturated, 16 g (50 g − 34 g) of potassium chloride will come out for 100 g of warm solution.

So, for 200 g of warm solution, 32 g potassium chloride will come out.

Conclusion:

Thus, 32 g of potassium chloride will come out of the solution when a warm solution containing 100 g of potassium chloride in 200 g of water is cooled to 20 $°C$ .