An unknown compound is found to have a molar mass of 392.16 g/mol. If the empirical formula is C2H5PF2, what is the molecular formula

C8H20P4F8

Explanation:

Molecular formula is based off a ratio of the molecular formula's molar mass divided by the empirical formula's molar mass.

The molar mass of the empirical formula C2H5PF2 is 98.02g. We find this by adding the molar masses of all elements in the formula, multiplied by their subscripts.

2(12.01) + 5(1.01) + 30.97 + 2(18.99) = 98.02

We then divide the molecular molar mass by the empirical molar mass.

392.16/98.02 = 4

This tells us that the molecular formula has 4 times the mass of the empirical formula. Because mass comes from the elements in the formula, we multiply all the subscripts by 4 to get the molecular formula.

2x4 = 8

5x4 = 20

1x4 = 4

2x4 = 8

So the molecular formula is C8H20P4F8