What will be the solubility of `Pb(OH)_2` in buffer of `pH=9` at `25^(@)C` provided the solubility of `Pb(OH)_2` in water is `6.67xx10^(-6)` (M) ?

Explanation

`Pb(OH)_2(s) `K_(sp)=[Pb^(2+)][OH^-]^2` or `=Sxx(2s)^2=4S^3`
[S =solubility]
`S=6.7xx10^(-6)`
`:.K_(sp)=4xx(6.7xx10^(-6))^3=1.2xx10^(-15)`
`pOH=14-pH=14-9=5`
`:.[OH^-]=10^(-15)=[Pb^(2+)]xx(10^(-5))^2`
or `1.2xx10^(-15)=[Pb^(2+)]xx(10^(-5))^2`
`:.[Pb^(2+)]=1.2x10^(-5)(M)`
`:.` solubility of `Pb(OH)_2=1.2xx10^(-5)mol*L^(-1)`