15.3 Exercise 15

A 0.125-M solution of Mn(NO₃)₂ is saturated with H₂S ([H₂S] = 0.10 M). At what pH does MnS begin to precipitate?

$\text{MnS} \left(s\right) \rightleftharpoons \text{Mn}^{\text{2}+} \left(a q\right) + \text{S}^{\text{2}−} \left(a q\right) K_{\text{sp}} = 2.3 \times 10^{−\text{13}}$

$\text{H}_{2} \text{S} \left(a q\right) + 2 \text{H}_{2} \text{O} \left(l\right) \rightleftharpoons 2 \text{H}_{3} \text{O}^{+} \left(a q\right) + \text{S}^{\text{2}−} \left(a q\right) K = 1.0 \times 10^{−\text{26}}$