Question

An aqueous solution contains Ni2+, Co2+ and Pb2+ ions at equal concentrations. The solubility product of Nis, PbS and CoS in water at 25°C are 1.4 x 10-24
3.4 x 10-28 and 3 x 10-26, respectively. Indicate which of these ions will be precipitated first and last when sulphide concentration is progressively
increased from zero?
ONIS and Pbs
NiS and Cos
CoS and NIS
O PbS and Nis​

Answer 1

Explanation:

For precipitation, ionic product > solubility product

The metal sulphide with lowest

will precipitate out first because its ionic product will exceed its

first and the metal sulphide with lowest

will precipitate out at last