What is the minimum pH required to prevent the precipitation of Zn^(+2) in a solution that is 0.01 M ZnCl_(2) and saturated with 0.1 M H_(2) S (Given : K_(sp) ZnS = 10^(-21) and Ka_(1) xx Ka_(2)of H_(2)S= 10^(-20) )

What is the minimum pH required to prevent the precipitation of Zn^(+2

1.	What is the minimum pH required to prevent the precipitation of Zn^(+2) in a solution that is 0.01 M ZnCl_(2) and saturated with 0.1 M H_(2) S (Given : K_(sp) ZnS = 10^(-21) and Ka_(1) xx Ka_(2)of H_(2)S= 10^(-20) )
Answer» Solution :`[Zn ^(+2) ] =0.01 M rArr K_(sp) = [Zn^(+2)][S^(-2)]` `10 ^(-21)= (10 ^(_2))[S^(-2)]rArr [S^(-2) ]=10 ^(-19)M` `H_2S hArr 2H^(+) +S^(-2)rArr K_(eq)=([H^(+)][S^(-2)])/( [H_2S]) ` ` 10 ^(-20)=([H^(+) ]^(2) (10^(-19)))/(10^(-1)) rArr [H^(+) ]=0.1 M` ` PH =1`