Answer: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
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.
(15.6/62.3018)*6.02214179*10^23
=> 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.
