The molar solubility of CaF2 (Ksp=5.3×10-11) in 0.1 M solution of NaF will be [2019]
(3)
CaF2→Ca2+s+2F-2s
NaF→Na+0.1 M+F-0.1 M
[Ca2+]=s, [F-]=(2s+0.1)≈0.1 M
Ksp=[Ca2+][F-]2
5.3×10-11=(s)(0.1)2
s=5.3×10-11(0.1)2=5.3×10-9 mol L-1
∴ Molar solubility is 5.3×10-9 mol L-1