posted by John on .
Tooth enamel is made up of hydroxyapatite, Ca_10(PO_4)_6(OH)_2 or the empirical formula, Ca_5(PO_4)_3(OH). Use the empirical formula for all calculations because stoichiometry plays two significant roles.
A. Print the balanced chemical equation for the molar solubility of hydroxyapatite in pure water. An appropriate arrow is expected.
B. Print the Ksp mass action or solubility product equilibrium concentration constant for the molar solubility of the insoluble solid in pure water.
C. Calculate the molar solubility of tooth enamel in pure water if the Ksp is 6.8X10^-37.
D. Recalculate the molar solubility in a 0.005 M calcium nitrate solution.
I would do this and found evidence on the web that the ionization products are as follows:
Ca5(PO4)3(OH) ==>5Ca^+2 + 3PO4^-3 + OH^-
Ksp = (Ca^+2)^5*(PO4^-3)^3*(OH)
C. Set up an ICE chart and substitute into the Ksp expression.
D. Do the same as C but substitute 0.005 for (Ca^+2).
Post your work if you get stuck.