What is the solubility of PbI2 in 0.4 M KI given the solubility constant of PbI2 is 7.1 x 10-9

Question

a. 3.5 x 10-3 M

b. 1.2 x 10-3 M

c. 4.4 x 10-8 M

Ksp = 7.1 x 10-9
Ksp = x * (2 * 0.4)
(7.1 * 10-9)/.8 = x
8.8 x 10-9 = x ------ But this is not one of the answers. Please help. I think the answer may be C. Am I correct? Thanks

Answer 1

The problem gives KI as 0.4M and not 2*0.4 and that term is squared and not to the first power.. Two errors.

Answer 2

7.1 x 10^-9 = x * (0.4M)^2
(7.1 x 10^-9)/.16 = x
4.4 x 10^-8 = x
is this the correct way to solve this problem?

Answer 3

yes

Answer 4

Thx Chris u da goat