What is the maximum concentration of equimolar solutions of ferrous sulphate and sodium sulphide so that when mixed in equal volumes, there is no precipitation of iron sulphide ? For iron sulphide, K_(sp)=6.3xx10^(-18).

What is the maximum concentration of equimolar solutions of ferrous su

1.	What is the maximum concentration of equimolar solutions of ferrous sulphate and sodium sulphide so that when mixed in equal volumes, there is no precipitation of iron sulphide ? For iron sulphide, K_(sp)=6.3xx10^(-18).
Answer» Solution :Suppose the CONCENTRATION of each of `FeSO_(4) and Na_(2)S ` is xmol `L^(-1)` . Then after mixing equal volumes, `[FeSO_(4)]=[Na_(2)S]=(x)/(2) M, i.e., [Fe^(2+)]=[S^(2-)]=(x)/(2)M` `F_(sp) "for" =[Fe^(2+)][S^(2-)] , i.e., 6.3xx10^(-18) = (x)/(2)xx(x)/(2)orx^(2) = 25.2 xx 10^(-18), or x =5.02xx10^(-9)M`.