posted by Lance on .
A gas containing carbon and hydrogen analyzed as 85.6 % carbon and 14.4 % hydrogen. A 42.1 g sample of a gas occupied a volume of 7490 mL with a pressure of 2280.0 torr at 92 °C. Enter the molecular formula of the compound.
1. Take a 100 g sample. This will give you 85.6 g C and 14.4 g H.
Convert to mols, then find the ratio of the elements to each other with the smallest number being 1.00. This will give you the empirical formula.
2. Find the molar mass from
PV = nRT and solve for n = number of mols. Then n = grams/molar mass; you know n and grams, solve for molar mass.
3. empirical formula mass*x = molar mass. Then x is the subscript in this formula. (empirical formula)x
Post your work if you get stuck.
Got it. thanks for the help!