1. Tooth enamel consists mainly of hydroxyapatite (Ca5(PO4)3(OH). When tin(II)fluoride is added to toothpaste it reacts with the enamel to produce a more decay-resistant material fluoroapatite ( Ca5(PO4)3F. The by-products of this reaction are tin(II)oxide and water. What mass of hydroxyapatite can be converted to fluoroapatite by reaction with 0.115 grams of tin(II)fluoride

The mass of hydroxyapatite that can be converted is 0.733 grams

Explanation:

To calculate the number of moles, we use the equation:

    .....(1)

Given mass of tin(II)fluoride  = 0.115 g

Molar mass of tin(II)fluoride = 156.7 g/mol

Putting values in equation 1, we get:

The chemical equation for the reaction of tin(II)fluoride and hydroxyapatite follows:

By Stoichiometry of the reaction:

1 mole of tin (II) fluoride reacts with 2 moles of hydroxyapatite

So, 0.00073 moles of tin (II) fluoride will react with = of hydroxyapatite

Now, calculating the mass of hydroxyapatite by using equation 1, we get:

Moles of hydroxyapatite = 0.00146 moles  

Molar mass of hydroxyapatite = 502.3 g/mol

Putting values in equation 1, we get:

Hence, the mass of hydroxyapatite that can be converted is 0.733 grams