# How to calculate the solubility of CaF2 at different temperatures?

At $\pu{25^\circ C}$ I used the free energy table for $G$ for the reaction and got $K_\mathrm{sp}= 10^{-9.02}$.

I now need to find out what the solubility is at $10$, $20$ and $\pu{30^\circ C}$. Could you also show what equation you used and how to work out the solubility by one of these other temperatures?

• Could you elaborate on how you might approach the problem first, rather than asking for a solution, I think it will be a lot more likely to receive an answer that way. – jonsca Oct 16 '12 at 6:48

You know how solubility is linked to dissolution reaction (Gibbs) free energy. Now, how does the free energy depend on temperature? In other words, what is $\displaystyle\frac{\partial G}{\partial T}$?
• I think you misread the results. The 20 C reading is the smallest. Assuming that Erin used a constant $\Delta H$, that's not possible. I'd guess that there is a math error involved. – Paul J. Gans Nov 16 '12 at 19:04