A sample of trifluoroacetic acid, C2HF3O2, contains 53.7 g of fluorine. Calculate the mass of the trifluoroacetic acid sample.

Answer 1

Molar mass C2HF3O2 = 114 g / mol

Atomic mass fluorine (F) = 19.0 g / mol

Each mol C2HF3O2 contains 3 mols F or 3 x 19.0 g = 57 g F

Let's convert that to percent F

57 g / 114 g (x100%) = 50%

Now we can find the mass of C2HF3O2 knowing that it contains 53.7 g F

53.7 g / x g = 0.50

x = 107.4 g = 107 g (3 sig. figs.)