Plz help me in this problem?

Question

Calculate the molar solubility of copper(II) sulfide in each of the following.

0.28M CuCl2

0.23M K2S

Answer 1

Ksp = [Cu++] [S--] = 8.0 x10 ^-37 (see source below)

Let molar solubility = x

Ksp = (x) (x).

if 0.28 M CuCl2 is present, then [Cu++]o = 0.28 M:

Ksp = (x + 0.28 M) (x)

Assume 0.28 >> x so we ignore x in the left parentheses

Ksp = (0.28 M) (x) = 8.0 x10 ^-37

Solving x = 2.9x10^-36 M.

By going through the same procedure with K2S, the exact same answer is obtained.