Chem question about tooth decay?

Question

Stannous fluoride or tin fluoride,SnF2, is an ingredient that is able to decrease tooth decay.

a. would you calculate the atomic mass, molecular mass, or formula mass of stannous floride? Explain how you came to this decision??

b. What is the value for SnF2??

c. Avogadro's number is equal to 6.0221 x 10^23. How many fluoride ions are in 15.00 g of stannous fluoride??

Answer 1

a) I would calculate the formula mass. Reason - that is the name of the substance you stated in your question.

b) Sn = 118.71 g/mole F = 19 g/mole so
SnF2 = 156.71 g/mole

c) 15 g * (mole/156.71g) * (*6.023*10^23 molecules/mole)
= 5.76 * 10^22 molecules

Each SnF2 molecule will give 2 F- ions

= 2.57 * 10^23 ions F-