How do I calculate the volume of a gas?

A 327 mL volume of an unknown gas at 24* C and 739 mm Hg had a mass of 339 mg. Calculate the molecular mass of the gas.?

• A 327 mL volume of an unknown gas at 24* C and 739 mm Hg had a mass of 339 mg. Calculate the molecular mass of the gas. a.) 20.8 amu b.) 26 amu c.) 24.6 amu d.) 22.0 amu e.) 52 amu

• Answer:

  In the ideal gas law, the n term can be replaced by the ratio of mass / molar mass. Making that substitution and rearranging gives: PV=(mass/MW) RT MW = mass RT / PV Convert your temperature, pressure and volumes into the appropriate units for your value of R, and express the mass in grams. Plugging in will let you calculate the molar mass: MW = (0.339 g) (0.0821 Latm/molK) (297 K) / 0.972 atm (0.327 L) MW = 26.0 g/mol