Chemistry - Ionic Equilibrium Question with Solution | TestHub

What should the ${\mathrm{H}}^{+}$concentration be in solution that is 0.25 M in ${\mathrm{Co}}^{2+}$ to prevent the precipitation of CoS when the solution is saturated with ${\mathrm{H}}_2\mathrm{S}$. A saturated solution of ${\mathrm{H}}_2\mathrm{S}$ is 0.1 M :-

$K_{\mathrm{sp}}(\mathrm{CoS})=5\times 10^{-22}$, $K_1({\mathrm{H}}_2\mathrm{S})=1.1\times 10^{-8}$, $K_{a2}({\mathrm{H}}_2\mathrm{S})=1.0\times 10^{-13}$