posted by Kasey .
To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 2.7L bulb, then filled it with the gas at 1.30 atm and 30.0 C and weighed it again. The difference in mass was 3.9 g. Identify the gas.
I used Pv=nRT to get the moles, but it keeps saying my answer is wrong. I don't know how to incorporate the difference in mass.
After you find moles, then
mol = grams/molar mass
You know mol and grams, solve for molar mass and divide by 2. Compare the answer with the periodic table to identify the gas.