what is Ksp for the saturated solution of silver phosphate?

Question

a saturated solution is formed when a salt is added to water until equilibrium is established between the undissolved salt and its ions in solution. this process can be represented by the equation:

Ag3PO4(s) 3Ag^+(aq) + PO4^3-(aq)

at a particular temperature, the concentration of silver ions in a saturated solution of silver phosphate is 1.26e-4 M. what is the equilibrium constant, Ksp, for this salt at this particular temperature?

Answer 1

Ag₃PO₄(s) ===> 3Ag⁺(aq) + PO₄^3-(aq)

Ksp = [Ag⁺]³[PO₄^3-]

If [Ag⁺] = 1.26x10^-4 M, the [PO₄^3-] = (1/3)(1.26x10^-4 M) = 4.2x10^-5 M

Ksp = (1.26x10^-4)³(4.2x10^-5)

Ksp = 8.4x10^-17