Chapter 23, Problem 23.18P

Interpretation Introduction

Interpretation:

The larger the partition coefficient, the longer it takes a solute to be eluted. Reason for this observation has to be given.

Concept introduction:

Partition coefficient:

Partition of a solute is depends on “like dissolves like” concept.  This means the solubility of solute is more in a solvent whose polarity is similar to that of the solute.

The partition coefficient of solute $\left(\text{S}\right)$ is given by

$\text{Solute}\left(\text{in}\text{phase}\text{1}\right)\stackrel{}{\rightleftharpoons }\text{Solute}\left(\text{in}\text{phase}\text{2}\right)$

$\begin{array}{l}\text{K=}\frac{{\text{A}}_{{\text{S}}_{\text{2}}}}{{\text{A}}_{{\text{S}}_{\text{1}}}}\approx \frac{{\left[\text{S}\right]}_{\text{2}}}{{\left[\text{S}\right]}_{\text{1}}}\\ \text{where,}\\ \text{K}\text{-}\text{partition}\text{coefficient}\\ {\text{A}}_{{\text{S}}_{\text{1}}}\text{-}\text{Activity}\text{of}\text{solute}\text{in}\text{phase}\text{1}\\ {\text{A}}_{{\text{S}}_{\text{2}}}\text{-}\text{Activity}\text{of}\text{solute}\text{in}\text{phase}\text{2}\\ {\left[\text{S}\right]}_{\text{1}}\text{-}\text{Concentration}\text{of}\text{solute}\text{in}\text{phase}\text{1}\\ {\left[\text{S}\right]}_{\text{2}}\text{-}\text{Concentration}\text{of}\text{solute}\text{in}\text{phase}\text{2}\end{array}$