# How does Ksp effect solubility?

Jun 13, 2016

${K}_{s p}$ is a MEASURE of solubility.

#### Explanation:

${K}_{s p}$, the $\text{sp}$ stands for $\text{solubility product}$, is another equilibrium constant, and measures the solubility of an insoluble or sparingly soluble salt. As with any equilibrium, standard conditions are assumed, i.e. $298 \cdot K$, and $1 \cdot a t m$ pressure.

The larger the ${K}_{s p}$ constant, the more soluble is the salt. Silver halides are the classic insoluble salts, and ${K}_{s p}$ measures the extent of the following reaction:

$A {g}^{+} + {X}^{-} \rightarrow A g X \left(s\right) \downarrow$

${K}_{s p}$ $=$ $\left[A {g}^{+}\right] \left[{X}^{-}\right]$ (of course $\left[A g X \left(s\right)\right]$ does not appear in this equilibrium expression in that we cannot speak of the concentration of a solid.

${K}_{s p} , A g X :$ X=Cl, 1.8xx10^-10;
X=Br, 5.0xx10^(-13);
$X = I , 8.5 \times {10}^{- 17}$

From the list, it is clear that $A g I$ is the least soluble species.

${K}_{s p}$ are extensively tabulated, especially for salts of precious metals. How do you think ${K}_{s p}$ values would evolve at higher temperatures? Say. $323 \cdot K$?