Chapter 14, Problem 109A

If you prepared a saturated aqueous solution of potassiumchloride at 25°C and then heated it to 50°C, wouldyou describe the solution as unsaturated, saturated, orsupersaturated? Explain.

Interpretation Introduction

Interpretation:

The solution have to be characterized from the solubility behavior.

Concept introduction:

Solubility can be defined as maximum amount of solute that can dissolve in known amount of solvent at a given temperature and pressure. Solubility of the solute in a particular solvent is affected by the change in temperature.

Solution is a homogeneous mixture of solute and solvent where a solute is fully dissolved in the solvent. Depending of amount of solute in a solution there are three types of solutions:

Unsaturated solution contains less amount of solute dissolved in a solvent for a given temperature and pressure than a saturated solution.

Saturated solution is a solution which contains maximum amount of solutedissolved in the solvent. If adding extra amount of solute to a saturated solution, the excess solutes get crystallized in the solution.

Supersaturated solution contains more dissolved solute than a saturated solution at the same temperature.

Answer to Problem 109A

When the temperature of a saturated KCl solution increases from $25°\mathrm{C}$ to $50°\mathrm{C}$, the solubility of the solution increases. Thus, the solution became unsaturated, so more amount of solute can be dissolved to make saturated solution again.

Explanation of Solution

Solubility of the solute in a particular solventincreases with increasingtemperature of the solution. When the temperature of a saturated KCl solution increases from $25°\mathrm{C}$ to $50°\mathrm{C}$, the solubility of KCl increases. Thus, the solution became unsaturated, so more amount of solute can be dissolved to make saturated solution again.