Answer to Question #63481 in General Chemistry for Ashley

Question

When acidified, the tooth enamel dissolves. The phosphate ions convert to hydrogen phosphate, and the hydroxide ion reacts with hydronium ion to make water. The overall equilibrium involves Ksp, Ka3 of phosphoric acid, and Kw. Ca5(PO4)3OH + 4H^+ → 5Ca^2+ +3HPO4^2- + H2O
a) Calculate the equilibrium constant for this reaction. K = Ksp / [(Ka33 x Kw] = ?
b) Show the three equations that apply.

When hydroxyapatite is treated with fluoride, the mineral fluorapatite, Ca5(PO4)3F, forms. The Ksp of this substance is 1 x 10^-60.
c) Calculate the transposition equilibrium constant for the conversion of the OH- to the F- form.