Question

A solution which is 10^-3M each in Mn²⁺, Fe²⁺ ,Zn²⁺ atd. Hg²⁺ is treated with 10^-16 M sulphide ion. lf K_sp of MnS, FeS, ZnS and HgS are 10^-15, 10 ^-23, 10^-20 and 10^-54 respectively, which one will precipitate first.

(a) FeS

(b) MgS

(c) HgS

(d) ZnS

Answer 1

The correct option (c) HgS

Explanation:

On the basis of precipitation concept an electrolyte will be precipitated firstly whose ionic product is exceeded to its solubility product. In similar ionic conc of cations, an electrolyte is precipitated firstly for which K_sp is lower. In these electrolytes MnS, FeS, ZnS, and HgS, HgS is precipitate firstly.