Problem: Tooth enamel consists of hydroxyapatite, Ca 5(PO4)3OH (Ksp = 6.8 × 10−37). Fluoride ion added to drinking water reacts with Ca5(PO4)3OH to form the more tooth decay–resistant fluorapatite, Ca5(PO4)3F (Ksp = 1.0 × 10−60). Fluoridated water has dramatically decreased cavities among children. Calculate the solubility of Ca5(PO4)3OH and of Ca 5(PO4)3F in water.

🤓 Based on our data, we think this question is relevant for Professor Quach's class at SEMINOLESTATE.

FREE Expert Solution

For Ca5(PO4)3OH: Since the Ca5(PO4)3OH is an ionic compound, it forms ions when dissociating in water. The dissociation of Ca5(PO4)3OH in water is as follows:

Ca5(PO4)3OH(s)  5 Ca2+(aq) + 3 PO43+(aq) +  OH(aq)



We can construct an ICE table for the dissociation of Ca5(PO4)3OH

Remember that solids are ignored in the ICE table and Ksp expression.

View Complete Written Solution
Problem Details

Tooth enamel consists of hydroxyapatite, Ca 5(PO4)3OH (Ksp = 6.8 × 10−37). Fluoride ion added to drinking water reacts with Ca5(PO4)3OH to form the more tooth decay–resistant fluorapatite, Ca5(PO4)3F (Ksp = 1.0 × 10−60). Fluoridated water has dramatically decreased cavities among children. Calculate the solubility of Ca5(PO4)3OH and of Ca 5(PO4)3F in water.