Determine the fluoride ion concentration for a saturated solution of magnesium flouride. (Ksp = 7.4E-11)
To determine the fluoride ion concentration for a saturated solution of magnesium fluoride, we need to use the solubility product constant (Ksp) for magnesium fluoride.
The equation for the dissociation of magnesium fluoride is:
MgF2 ⇌ Mg^2+ + 2F^-
According to the stoichiometry of the reaction, for every one mole of magnesium fluoride that dissolves, it generates one mole of magnesium ions (Mg^2+) and two moles of fluoride ions (F^-).
The solubility product constant (Ksp) expression for magnesium fluoride is:
Ksp = [Mg^2+][F^-]^2
Since the concentration of magnesium ions (Mg^2+) depends on the solubility of magnesium fluoride, we need to assume that all the magnesium fluoride has dissolved in the saturated solution. Therefore, the concentration of magnesium ions can be considered negligible compared to the concentration of fluoride ions.
Hence, we can simplify the Ksp expression to:
Ksp = [F^-]^2
Rearranging the equation, we can solve for the concentration of fluoride ions ([F^-]):
[F^-] = √(Ksp)
Substituting the given value for Ksp:
[F^-] = √(7.4E-11)
Calculating this expression will give us the concentration of fluoride ions in the saturated solution of magnesium fluoride.