What is the minimum pH required to prevent the precipitation of ZnS in a solution that is `0.01 M ZnCl_2` and saturated with `0.10 M H_2S`? Given `K_(sp)` of `ZnS=10^(-21)` , for `H_2S K_(a_1)xK_(a_2)=10^(-20)`

Answer

1

Explanation

`K_(sp)=[Zn^(2+)][S^(-2)]`
:. [5^2]=10^(-21)/10.01=10^(-19)`
`K_(a_1)xxK_(a_2)=([H^+]^(2)[10^(-19)])/0.1implies 10^(-20)=([H^+]^(2)[10^(-19)])/0.1`
`[H^+]=10^(-1)`
pH=1