How Does Filling a Canister with Oxygen Affect Its Weight?

[Luongo]

An empty cylindrical canister 1.60m long and 89.0cm in diameter is to be filled with pure oxygen at 27.0 C to store in a space station. To hold as much gas as possible, the absolute pressure of the oxygen will be 21.3atm . The molar mass of oxygen is 32.0g/mol. How many moles of oxygen does this canister hold? For someone lifting this canister, by how many kilograms does this gas increase the mass to be lifted?

So what i did was got the volume of cylinder using V = pi r^2 h
im (m^3) i multiplied by 1000 to get it in litres. 3981L
then i just plugged in n= 3981L (21.3atm) / .08206 (300K)
what am i doing wrong? shudnt i get the moles in the canister 3445 moles.

Homework Statement

Homework Equations

The Attempt at a Solution

 

[Redbelly98]

So what i did was got the volume of cylinder using V = pi r^2 h
im (m^3) i multiplied by 1000 to get it in litres. 3981L
then i just plugged in n= 3981L (21.3atm) / .08206 (300K)
what am i doing wrong? shudnt i get the moles in the canister 3445 moles.

Your answer looks good to me, but if you are graded on significant figures you'll want to consider that.