Tooth enamel consist mainly of hydroxyapatite (Ca5(PO4)3(OH). When tine (II) Flouride is added to toothpaste it reacts with the enamel to product a more decay-resistant material fluorapatite (Ca(PO4)3F. The by-products of this reaction are tin (II) oxide and water. What mass of hydroxypatite can be converted to fluoroapatite by reaction with 0.115 grams of tin (II) fluoride? Write a balanced reaction first.

Answer 1

Note you have the wrong formula for fluorapatite. It is Ca5(PO4)3F.

2Ca5(PO4)3(OH) + SnF2 ==> 2Ca5(PO4)3F + SnO + H2O

This is just like the problem I did for you last night. These stoichiometry problems are done the same way. A four step process.
1. Write and balance the equation. I've done that for you above.

2. Convert what you have (in this case SnF2) to mols. mols = grams/molar mass = ?

3. Convert mols of what you have (mols of SnF2) to mols of what you want (mols of hydroxyapatite). You do this by using the coefficients in the balanced equation.

4. Now convert mols of what you want into grams. grams Ca5(PO4)3(OH) = mols x molar mass

Post your work if you run into trouble.

Answer 2

Thanks