What is the mass, in grams of 2.80 L of CO2 at STP (Standard pressure) ?

-The topic i'm learning is Gas laws

Assuming that CO2 is an ideal gas, we use the equation PV=nRT to determine n and multiply by molar mass to obtain mass. At STP, temperature is equal to 298.15 K and pressure is 1 atm.

PV = nRT

n = PV / RT

n = 1 (2.80) / 0.08205 (298.15)

n = 0.1145 mol

mass = 0.1145 (44.01) = 5.04 g CO2