The concentration of sulphide ion in 0.1 M HCI solution saturated with hydrogen sulphide is 1.0 xx10^(-19) M. If 10 mL of this solution is added to 5 ml of 0.04 M solution of FeSO_4, MnCl_2, ZnCl_2 and CdCl_2, in which solutions precipitation will take place? (Given K_(sp)for FeS = 6,3 xx10^(-18) , MnS = 2.5 xx10^(-13), ZnS = 1.6 xx10^(-24) and CdS = 8.0 xx10^(-27).)

The concentration of sulphide ion in 0.1 M HCI solution saturated with

1.	The concentration of sulphide ion in 0.1 M HCI solution saturated with hydrogen sulphide is 1.0 xx10^(-19) M. If 10 mL of this solution is added to 5 ml of 0.04 M solution of FeSO_4, MnCl_2, ZnCl_2 and CdCl_2, in which solutions precipitation will take place? (Given K_(sp)for FeS = 6,3 xx10^(-18) , MnS = 2.5 xx10^(-13), ZnS = 1.6 xx10^(-24) and CdS = 8.0 xx10^(-27).)
Answer» `FeSO_4` `MnCI_2` `ZnCI_2` `CdCI_2` Solution :When `K_(ip)gtK_(sp)` precipition takesplace, as10 MLOF solutioncontaining`S^(2-)`ionis mixedwith5mLofmetalsaltsolution, aftermixing `[s^(2-)]=1.0 xx10^(-19) xx (10)/(15 ) =6.67 xx 10^(-20)` `[Fe^(2+)] = [Mn^(2+)] = [Zn^(2+)] = [Cd^(2+)]` `=(5)/( 15) xx 0.04 = 1.33 xx 10^(-2)M` ` therefore ` Ionicproduct FOREACH of thesewill be ` =[M^(2+)] [S^(2-)]` `=(1.33 xx 10^(-2) ) ( 6.67 xx 10^(-20)) = 8.87 xx 10^(-22)` asthisvalueis greater than the solubilityproductof ` ZnS ` andCdstherefore`,ZnCI_2`and `CdCI_2`solutionswillbe precipitatedwhereasFeSand MnSis lesserthansolubilityproductthereforeprecipitationdoes nottakeplacein thiscase .