A solution which is 10-3 M each in Mn2 + , Fe2 + , Zn2 + and Hg2 + is treated with 10 - 16 M sulphide ion. If Ksp of MnS, FeS, ZnS and HgS are 10 - 13 , 10-18 , 10-24 and 10-53 respectively, which one will precipitate first ?

Question

A solution which is 10-3 M each in Mn2 + , Fe2 + , Zn2 + and Hg2 + is treated with 10 - 16 M sulphide ion. If Ksp of MnS, FeS, ZnS and HgS are 10 - 13 , 10-18 , 10-24 and 10-53 respectively, which one will precipitate first ? (A) FeS (B) MgS (C) HgS (D) ZnS

Tardigrade Admin · Accepted Answer

[S2 - ] need for precipitation of textFeS = (1 0- 1 8/1 0- 3) = 1 0- 1 5 textM textMnS = (1 0- 1 3/1 0- 3) = 1 0- 1 0 textM textHgS = (1 0- 5 3/1 0- 3) = 1 0- 5 0 textM textZnS = (1 0- 2 4/1 0- 3) = 1 0- 2 1 textM Thus minimum [S2 - ] for precipitation is for HgS it will be precipitated first.

Q. A solution which is 10-3 M each in Mn2 + , Fe2 + , Zn2 + and Hg2 + is treated with 10 - 16 M sulphide ion. If Ksp of MnS, FeS, ZnS and HgS are 10 - 13 , 10-18 , 10-24 and 10-53 respectively, which one will precipitate first ?

FeS

MgS

HgS

ZnS

[S2 - ] need for precipitation of FeS=10−310−18​=10−15M MnS=10−310−13​=10−10M HgS=10−310−53​=10−50M ZnS=10−310−24​=10−21M Thus minimum [S2 - ] for precipitation is for HgS it will be precipitated first.

Q. A solution which is 10^-3 M each in Mn²⁺ , Fe²⁺ , Zn²⁺ and Hg²⁺ is treated with 10^{- 16} M sulphide ion. If K_sp of MnS, FeS, ZnS and HgS are 10^{- 13} , 10^-18 , 10^-24 and 10^-53 respectively, which one will precipitate first ?