Question

At 25 °C only 0.0580 mol of the generic salt AB3 is soluble in 1.00 L of water. What is the Ksp of the salt at 25 °C?

Answer 1

s = 0.0580 g/L
s = 5.80*10^-2 g/L

The salt dissolves as:
AB3       <---->     A3+      +         3 B-    

                     s                  3s      

Ksp = [A3+][B-]^3
Ksp = (s)*(3s)^3
Ksp = 27(s)^4
Ksp = 27(5.80*10^-2)^4
Ksp = 3.055*10^-4
Answer: 3.055*10^-4