If there are 5 liters of oxygen gas (O2) at 300 K and 400 torr, what will it weigh?

Answer in units of g.

Do I use the Ideal gas law formula for this problem?

3 answers

Yes, use PV = nRT and solve for n, then
n = grams/molar mass and solve for grams.
When I use this formula do I have to convert torr to atm and mL to L?
I got around 5.48g...
I think it's wrong