A sample of trifluoroacetic acid

Question

A sample of trifluoroacetic acid, C2HF3O2, contains 54.5 g of oxygen. Calculate the mass of the trifluoroacetic acid sample.

Answer 1

You can use dimensional analysis and the fact that 1 mol of trifluoroacetic acid (TFA) contains 2 moles of O, according to the formula C₂HF₃O₂. Molar mass TFA = 114 g / mol

54.5 g O x 1 mol O / 16 g x 1 mol TFA / 2 mol O x 114 g TFA / mol = 194 g TFA