Tooth enamel is composed of hydroxyapatite, whose simplest formula is Ca5(PO4)3OH, and whose corresponding Ksp = 6.8 X 10-27. As discussed in the "Chemistry and Life" box on page 730, fluoride in fluorinated water or in toothpaste reacts with hydroxyapatite to form fluoroapatite, Ca5(PO4)3F,whose Ksp = 1.0 X 10-60 .
(a)Write the expression for the solubility-constant for hydroxyapatite and for fluoroapatite .
(b) Calculate the molar solubility of each of these compounds.