Problem: What is the solubility of CaF2 (assume Ksp = 4.0 x 10-12 ) in 0.030 M NaF?

FREE Expert Solution

For this problem, we’re being asked to calculate the solubility of CaF2(s) in 0.300 M NaF(aq). Since the compounds are ionic compounds, they form ions when dissociating in water. The dissociation of CaF2 and NaF in water are as follows:


Calcium is in Group 2A so it’s charge is +2. Fluorine is in Group 7A so its charge is –1:

CaF2(s)  Ca2+(aq) + 2 F(aq)


Sodium is in Group 1A so it’s charge is +1. Fluorine is in Group 7A so its charge is –1:

NaF(s)  Na+(aq) + F(aq)


Notice that there is a common ion present, F. The common ion effect states that the solubility of a salt is lower in the presence of a common ion.


We can construct an ICE table for the dissociation of CaF2. Remember that solids are ignored in the ICE table.

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Problem Details

What is the solubility of CaF2 (assume Ksp = 4.0 x 10-12 ) in 0.030 M NaF?