Posted by liz on Wednesday, August 1, 2012 at 7:20pm.
Calculate the formula wright of a 2.50 g sample of gas whose volume is 1.40l at STP.

chem  DrBob222, Wednesday, August 1, 2012 at 8:50pm
Use PV = nRT and solve for n = number of mols; then n = grams/molar mass. You know n and grams, solve for molar mass (formula weight).
OR, if you remember that a gas at STP occupies 22.4 L, then
1.40 L/22.4 = n, then n = grams/molar mass.