Chapter 13, Problem 95SCQ

Interpretation Introduction

Interpretation: The reason of lowering in the freezing point of water by $1.5$ times by the addition of $CaC{l}_2$ than that of $NaCl$ has to be explained.

Concept introduction:

Colligative properties: Properties of solutions which having influence on the concentration of the solute in it. Colligative properties are,

• Decrease in the vapor pressure
• Increase in the boiling point
• Decline in the freezing point
• Osmotic pressure

Freezing point depression: The freezing point of the solution varies with the solute concentration.

$\begin{array}{c}\text{Freezing point depression = }\Delta {\text{T}}_{fp}{\text{= K}}_{fp}{\text{. m}}_{solute}\text{.i,}\\ \text{where,}{\text{K}}_{fp}\text{=}\text{molal freezing point depression constant,}\\ {\text{m}}_{solute}\text{= molality of solute,}\\ \text{i}\text{=}\text{van't}\text{Hoff}\text{factor}\text{.}\end{array}$