Determine the solubilities of silver chromate, barium chromate, ferric hydroxide, lead chloride and mercurous iodide at 298 K form their solubility product constants given below. Determine also the molarities of individual ions.
`K_(SP(Ag_(2)CrO_(4)))=1.1xx10^(-12)`,
`K_(SP(BaCrO_(4)))=1.2xx10^(-10)`,
`K_(SP[Fe(OH)_(3)])=1.0xx10^(-38)`,
`K_(SP(PbCI_(2)))=1.6xx10^(-5)`,
`K_(SP(Hg_(2)I_(2)))=4.5xx10^(-29)`.

Explanation

(i) For silver chromate
`Ag_(2)CrO_(4)` dissolves in water as follows:
`Ag_(2)CrO_(4)(s)hArr 2Ag^(+)(aq) +CrO_(4)^(2-) (aq)`
Let the solubility of salt in water =S
`[Ag^(+)(aq)]=2S, " and "[CrO_(4)^(2-) (aq)] =S , K_(sp) = [Ag^(+) (aq)]^(2)[CrO_(4)^(2-) (aq)]`
`1.10 xx10^(-12) =(2S)^(2) xx (S) =4S^(3)`
`" or "" " S=((1.10xx10^(-12))/(4))^(1//2) =0.65 xx 10^(-4) M`
Molarity of `Ag^(+)` ions `[Ag^(+)] =2S =2 xx 0.65 xx 10^(-4) =1.30 xx 10^(-4) M`
Molarity of `CrO_(4)^(2-) " ions " [CrO_(4)^(2-)] =S =0.65 xx 10^(-4) M`
(II) For barium chromate
`BaCrO_(4)` dissolves in water as follows:
`BaCrO_(4)(s) hArr Ba^(2+) (aq) +CrO_(4)^(2-) (aq)`