How many molecules of fluorine are in 15.6 grams of MgF2?  

Expert Answers
justaguide eNotes educator| Certified Educator

The number of molecules of magnesium fluoride in 15.6 g of MgF2 has to be found.

The molecular mass of MgF2 is 62.3018. 15.6 g of MgF2 is equivalent to 15.6/62.3018 mole of MgF2.

One mole of a gas has 6.02214179*10^23 particles.

15.6/62.3018 mole of MgF2 has (15.6/62.3018)*6.02214179*10^23 molecules of the compound.


=> 1.5079*20^23

If this is rounded to one decimal figure the result is 1.51*10^23.

The number of molecules of MgF2 in 15.6 g of the gas is 1.51*10^23.

hcteach eNotes educator| Certified Educator

You can set up stoichiemetry using the following equation:

(15.6 g MgF2) x (38g F / 62g MgF2) x (6.022x10^23 / 19gF)

= 3.03 x 10^23 molecules of F

or 1.52 x 10^23 molecules of F2