Chapter 12, Problem 12.110QP

Interpretation Introduction

Interpretation:

Freezing point of a solution at given Osmotic pressure and temperature has to be calculated.

Concept Introduction:

In the process of osmosis, the solvent molecules pass through a semi - permeable membrane from less concentrated solution to more concentrated solution.  The pressure that has to be applied to prevent the flow of solvent molecules is called osmotic pressure.  It is expressed as,

$\pi =MRT$

Where,

$\begin{array}{l}\text{π}\text{= osmotic pressure}\\ \text{M}\text{= Molar concentration}\\ \text{R}\text{= Universal gas constant}\\ \text{T}\text{= Temperature}\end{array}$

Freezing point of a liquid is defined as the temperature at which liquid becomes solid and the two phases remain in equilibrium with each other.

Freezing point of a substance can be determined by the formula,

$\Delta T_f=i\times K_{f}m$

Where,

$\begin{array}{l}\Delta T_f\text{ = depression in freezing point}\\ {\text{K}}_f\text{ = cryoscopic constant}\\ \text{m = molality of the solution; i = van't Hoff factor}\end{array}$