# How do we find gram solubilities of metal hydroxides?

Apr 30, 2017

You need to quote ${K}_{\text{sp}}$ values for the hydroxides of metal ions........

#### Explanation:

The ${K}_{\text{sp}}$ values are of course available in the literature, and SHOULD have been included in the question.

Once we have ${K}_{\text{sp}}$ values, then we can address the various solubility. For calcium chloride we approach this in this manner........

$C a {\left(O H\right)}_{2} \left(s\right) r i g h t \le f t h a r p \infty n s C {a}^{2 +} + 2 H {O}^{-}$

Now ${K}_{\text{sp}} = \left[C {a}^{2 +}\right] {\left[H {O}^{-}\right]}^{2}$.

And if we call the solubility of calcium chloride, $S$, then $S = \left[C {a}^{2 +}\right]$, and $\left[C {l}^{-}\right] = 2 S$ (provided there is no extraneous source of calcium and chloride ions......)

So ${K}_{\text{sp}} = S \times {\left(2 S\right)}^{2} = 4 {S}^{3}$.

And S=""^3sqrt((K_"sp")/4).

And so without ${K}_{\text{sp}}$ we are at an impasse. Such calculations require prior measurement or reference to the literature data.