Colligative Properties

Question

A solution consists of 0.50 mole of CaCl^2 dissolved in 100 grams of H^20. Compared to the boiling point and freezing point of 100 grams of water at the same pressure the solution has a high or lower boiling point and a high or lower freezing point

Answer 1

When a solute is dissolved in a solvent, the boiling point of the solution increases, and the freezing point of the solution decreases. This is due to the phenomenon called boiling point elevation and freezing point depression, respectively.

In the case of your solution, you have 0.50 mole of CaCl2 dissolved in 100 grams of H2O. CaCl2 is an ionic compound that dissociates into ions when dissolved in water. For each formula unit of CaCl2, it dissociates into one Ca^2+ ion and two Cl^- ions, so it has a van't Hoff factor (i) of 3.

Compared to the boiling point and freezing point of 100 grams of water at the same pressure, the solution with CaCl2 will have:

1. A higher boiling point, because the presence of solute particles raises the boiling point of the solution.

2. A lower freezing point, because the presence of solute particles lowers the freezing point of the solution.