Question

Using the molar volume (STP) or the ideal gas law equation, determine the molar mass,g/mole, of each of the following.
A: 11.2g of a gas that has a volume of 1.50Lat STP?
B: .0710g of a gas that has a volume 825ml at 1 atm

Answer 1

The molar volume is 22.4 L/mol.
1.50L/22.4 = n = #mols.
Then mols = grams/molar mass. You know mols and grams, solve for molar mass.

For B, if that is at standard T (273K), then 825/22,400 = mols.
mol = g/molar mass. If not at 273 K, use PV = nRT and solve for n, then n = grams/molar mass.