To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 2.8-L bulb, then filled it with the gas at 1.20atm and 22.0 ∘C and weighed it again. The difference in mass was 3.9g . Identify the gas.

Answer 1

Use PV = nRT, substitute the conditions and solve for n = number of mols. Then n = grmas/molar mass. You know mols and grams, solve for molar mass. Look on the periodic table and identify the gas.