A liquid was analyzed to be 54.5% C, 9.10% H, and 36.4% O. An empty flask, whose mass was 45.32 g, when filled with the vapor of the liquid at 735mm Hg and 99.2°C had a mass of 46.05 g. The volume of the flask was found to be 263.2 mL.

Question

A liquid was analyzed to be 54.5% C, 9.10% H, and 36.4% O. An empty flask, whose mass was 45.32 g, when filled with the vapor of the liquid at 735mm Hg and 99.2°C had a mass of 46.05 g. The volume of the flask was found to be 263.2 mL.
 
empirical formula -> C2H4O
 
What is the molecular formula of the compound?

DrBob222 · Answer

mass vapor = 46.05-45.32 = 0.73g
Use PV = nRT
Solve for n = number of mols
Then mol = grams/molar mass
You have grams and mol solve for molar mass.
molar mass/empirical mass = x. Round to whole number and
molecular formula = (C2H4O)*x

josh · Answer

thank you so much!