Calculate the solubility of `CoS` in `0.1M H_(2)S` and `0.15M H_(3)O^(oplus) (K_(sp)` of `CoS = 3 xx 10^(-26))`.
`(K_(1) xx K_(2) (H_(2)S) = 10^(-21))`

Explanation

a. `H_(2)O +H_(2)S overset(K_(1))hArrH_(3)O^(oplus) +HS^(Θ)`
`H_(2)O +HS^(Θ) overset(K_(2))hArrH_(3)O^(oplus) +S^(2-)`
`K_(1)K_(2) = ([H_(3)O^(oplus)]^(2)[S^(2-)])/([H_(2)S])=10^(-21)`
In `0.1M H_(2)S` and `0.15M H_(3)O^(oplus)`
`[S^(2-)] = ((0.15)^(2)[S^(2-)])/(0.1) = 10^(-21)`
`:. [S^(2-)] = (10^(-22))/(0.0225) = 4 xx 10^(-21)`
`K_(sp) = [Co^(2+)] [S^(2-)] = 3 xx 10^(-26)`
`[Co^(2+)] = (3xx10^(-26))/(4xx10^(-21)) = 7 xx 10^(-6)M`