At 25 °c only 0.0470 mol of the generic salt ab3 is soluble in 1.00 l of water. what is the ksp of the salt at 25 °c?

When we have the balanced equation for this reaction:

AB3 ↔ A+3 + 3B-

So we can get Ksp:

when Ksp = [A+3][B-]^3

when [A+3] = 0.047 mol and from the balanced equation when

1 mol [A+3] → 3 mol [B-]

0.047 [A+3] →?

[B-] = 3*0.047 = 0.141

so by substitution in Ksp formula:

∴Ksp = 0.047 * 0.141^3

= 1.32x10^-4