Question

what is the volume occupied by 16.0g ethane gas (C2H6) at 720 Torr and 18C?

V=nRT/P

conversion of mol:
16.0g C2H6 X 1mol C2H6/30.07g C2H6= .53mol C2H6

V= .53 mol(0.0821 L*atm/mol*K)(291)K /
720 Torr (1 atm/760Torr)

V= 13.5 L

Answer 1

Here is a quick check. You have a half mole at near stp. About 11 liters. But in reality, your pressure is about ten percent lower than stp, so volume about 12 liters, and temp is about 5 percent higher, so volume is about 13 liters.

I would go with your answer.