What is the solubility of MgF2 in water? The Ksp for MgF2 is 7.4*10^-11?

Answer 1

For each m moles of MgF2 that dissolves, there is m ions of Mg+2 and 2m ions of F-. So for Ksp,
m (2m)^2 = 74 x 10^-12 (this is a more useful form)
4m^3 = 74 x 10^-12 and m^3= 18.5x10^-12
m = 2.6x10^-4 mole/L appx.