Question

What is the ratio of mole $Mg(OH{)}_2$ and $Al(OH{)}_3$ in one litre in their saturated solution? $K_{sp}$ of $Mg(OH{)}_2=4\times {10}^{-12},Al(OH{)}_3=1\times {10}^{-33}$ Give answer by multiplying it with ${10}^{-17}$

Answer 1

$Mg(OH{)}_2\rightleftharpoons M{g}^{2+}+2O{H}^{-}$
$xx+2x$
$Al(OH{)}_3\rightleftharpoons A{l}^{3+}+3O{H}^{-}$
$yy+3y$ $K_{sp}=4\times {10}^{-12}=x(3y+2x{)}^2\text{and}{10}^{-33}=y(3y+2x{)}^3$ $\frac{x}{y}=8\times {10}^{17}\times {10}^{-17}=8$