Factors that Affect the Solubility Product Constant

Factors That Affect the Solubility Product Constant 

The true or thermodynamic solubility product constant K p will, for most substances, increase with the temperature by an amount that depends on the heat of solution. The addition of any organic solvent such as alcohol to an aqueous solution will generally result in a lower Kjp. This may be easily understood in terms of the increased work of separation of ions in a medium orxlower dielectric constant. 

Calculations involving precipitation equilibria involve yet another difficulty, namely the slow equilibration of the solid phase with the solution. Thus, kinetic effects may give rise to results which deviate significantly from those calculated. 

In dealing with solubility equilibria, it is usually assumed that the solid phase or precipitate is pure. In practice this is rarely achieved and at best only approximately so. For this reason separations that are predicted without taking such contamination into account are never fully realized. 

The effect of changing ionic strength on the value of the concentration solubility product constant K p, already briefly mentioned above, is even more significant than the corresponding effect on monoprotic acid dissociation constants. 

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