Answer to Question #154282 in General Chemistry for Jim Tulfo

Question

The concentration of B⁻ in a saturated solution of AB₃ is 1.10 x 10⁻⁵ mg/L. What is the Ksp of AB₃ if the MM of B is 17.0 g/mol? 

Answer 1

AB₃ = A⁺ + 3B^-

1.10 x 10^-5 mg/L = 1.10 x 10^-8 g/L

[B] = 1.10 x 10^-8 / 17.0 = 6.47 x 10^-10 (mol/L)

[A⁺] = 1/3 [B^-] = 1/3 x 6.47 x 10^-10 = 2.16 x 10^-10 (mol/L)

K_sp = [A⁺][B^-]³ = 2.16 x 10^-10  x (6.47 x 10^-10)³ = 5.84 x 10^-38