At 25 °C, the molar solubility of silver phosphate is #1.8 × 10^-5# mol L-1. How do you calculate Ksp for this salt?
Let's start by writing the chemical reaction for the dissociation of silver phosphate:
Now, set the Ksp value equal to the products (you don't care about the reactants because it's a solid). Ag is raised to the 3rd power because the coefficient is 3.
Replace each reactant with the letter x because that's what you're trying to find. Since the coefficient in front of silver is 3, a 3 must be placed in front of the x and it must be raised to the 3rd power.
Now you're left with
The value of x that we just obtained is our molar solubility.