How does recrystallization work

Like all equilibrium constants, the value of Repartition) depends on temperature, sometimes strongly so. It also depends on the solvent polarity. For example, K(partition) 

An alternative way of expressing the partition constant of a sparingly soluble salt is to define its solubility product Rsp (also called the solubility constant Rs). Ks is defined as the product of the ion activities of an ionic solute in its saturated solution, each raised to its stoichiometric number v . Ks is expressed with due reference to the dissociation equilibria involved and the ions present. 

We saw above how the extent of partition is temperature dependent in that example, excess air was expelled from solution during freezing, since the solubility of air was exceeded in a cold freezer box, and the gas left solution in order for the value of R(partition) to be maintained. 

The energy necessary to dissolve 1 mol of solute is called the enthalpy of solution Absolution) (cf- P- 125). A value of AH can be estimated by analysing the solubility s of a solute (which is clearly a function of Repartition)) w t 1 temperature T. 

The value of R(partition) changes with temperature the temperature dependence of an equilibrium constant is given by the van t Hoff isochore  

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