An unknown gas is placed in a 1.500 L bulb at a pressure of 356 mm Hg and a temperature of 22.5 ∘C, and is found to weigh 0.8108g .What is the molecular mass of the gas?

Answer 1

Use PV = nRT and solve for n = number of mols. Then n = grams/molar mass. You know n and grams, solve for molar mass.
Don't forget P is in atm, V in L and T in kelvin

Answer 2

Pv_nr0