What is the logarithm of the molar concentration of this salt?? CAN ANYONE HELP WITM THIS PROBLEM!!!!!?

Question

Consider a salt of composition, A2B3. For this salt, pKsp = 81.412. What is the logarithm of the molar concentration of this salt?

Can Anyone HELP ME WITH THIS PROBLEM!?!

Answer 1

if pK = 81.412 , ..... then K = 3.87e-82

A2B3 --> 2A  &  3B

X    ---->  2X   &  3X

3.87e-82 = [A]^2 [B]^3

3.87e-82 = [2X]^2 [3X]^3

3.87e-82 = (4X^2)(27X^3)

3.87e-82 = 108X^5

X5 = 3.583e-84

X = 2.0458 e-17

your answer is 2.05e-17 Molar

log = -16.689