A 0.6996 g sample of a compound containing C, H, and F was burned to produce 0.6039 g CO2 and 0.1235 g H2O. If the molar mass of the compound was determined to be approximately 102.0 g/mol, what is its molecular formula?

Question

A 0.6996 g sample of a compound containing C, H, and F was burned to produce 0.6039 g CO2 and 0.1235 g H2O. If the molar mass of the compound was determined to be approximately 102.0 g/mol, what is its molecular formula?

Answer 1

.6996g of sample at 102g/mol = 0.006859 mol

.6039g CO₂ at 44g/mol = 0.1373 mol of C
.1235g H₂O at 18g/mol = 0.006859 mol of H

so, each mole of the compound produces 2 moles of H and 2 moles of C

The formula is C₂H₂F_?

C₂H₂ has mass 26
102-26 = 76
Fluorine has mass 19
76/19 = 4

The compound has formula C₂H₂F₄