A liquid hydrocarbon (Cx Hy) is found to be 16.37% H by mass. A 1.158-g vaporized sample of the hydrocarbon has a 358 mL volume at 71.0 C and 749 mmHg. what is the molecular formula for this hydrocarbon?

Answer 1

Calculate the Empirical Formula given 16.37% H and (100-16.37)% C. Refer to Example #2.

http://www.chem.tamu.edu/class/majors/tutorialnotefiles/empirical.htm

Use PV=nRT.
n=mass/molar mass
units: P=atm, V=L, T=K
R=0.08206 atm*L/mol*k

Solve for molar mass and calculate the Molecular Formula.

http://chemistry.about.com/od/workedchemistryproblems/a/Molecular-Formula-Simplest-Formula-Example-Problem-1.htm