Chemistry

Problem

Determine the minimum concentration of fluoride ion,

\mathrm{F^-}

, required to initiate precipitation of

\mathrm{CaF_2}

in a

0.010\;\text{M}

\mathrm{Ca^{2+}}

solution at

25^\circ\text{C}

given that

K_{sp}(\mathrm{CaF_2}) = 3.9\times10^{-11}

. a)

8.8\times10^{-5}\;\text{M}

6.2\times10^{-5}\;\text{M}

3.9\times10^{-9}\;\text{M}

6.2\times10^{-6}\;\text{M}