Tooth Enamel Is Composed of the Mineral Hydroxyapatite $\rightleftarrows$ Ca₅ (PO₄)₃⁺(aq) + OH^-(aq)
Ca₅ (PO₄)₃(OH)(s) + H⁺(aq)

question 33

Multiple Choice

Tooth enamel is composed of the mineral hydroxyapatite. It is essentially insoluble in water with K_sp = 2.3* 10^-59, but it reacts with weak acids in the mouth as described by one of the reaction equations below. You can determine the equilibrium constant, K, for this reaction from K_sp and K_w (the equilibrium constant for water autoionization) . How do you do this?
Ca₅ (PO₄) ₃(OH) (s) $\rightleftarrows$ Ca₅ (PO₄) ₃⁺(aq) + OH^-(aq)
Ca₅ (PO₄) ₃(OH) (s) + H⁺(aq) $\rightleftarrows$ Ca₅ (PO₄) ₃⁺(aq) + H₂O(l)

• A) K = K_wK_sp
• B) K = K_w /K_sp
• C) K = K_sp /K_w
• D) K = K_w - K_sp
• E) K = K_w + K_sp