If a balloon filled with carbon dioxide has occupies a volume of 31 L at STP, what is the 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 molar mass, solve for grasm.

Another way to do it is to recognize that at STP 1 mol of a gas occupies 22.4 L. So mol = 31/22.4 and that x molar mass = grams.