Question

Write the Solubility Product Constant (Ksp) expression for the following solution at 275 oC.

MgF2(s)Mg2+(aq) + 2 F-(aq)

Answer 1

$K_{sp}=[Mg^{2+}][F^-]^2$

At $25^0C$ $K_{sp}=5.6\times10^{-11}$

At $275^oC$ we should use Van't Hoff equation

$lnK = (\frac{-\Delta H^o}{R})\times \frac{1}{T} + \frac{\Delta S^0}{R}$