Mass of Gas Equation

An 8.00L vessel at 25 degrees C contains oxygen(O2) gas at a pressure of 1.30 atm. What is the mass of the oxygen in the vessel?

Calculate moles of O2 using the gas law equation:
PV = nRT
1.30*8 = n*0.082057*298
n = 10.4/24.45
n = 0.425 mol O2
Molar mass O2 = 32g/mol
0.425mol = 0.425*32 = 13.61g O2 in vessel.

PV=nRT ....R= 0.08205746 L atm K−1 mol−1 .....T=273 +25=298 K

n=RT/PV = 0.08205746*298/(1.30*8.00) = 2.35 mole

molar mass of O2 = 32

mass of oxygen = 32*2.35 = 75.2 g

V = 8 L = 0.008 m^3
T = 25 deg. C = 298 K
Mr = 32 g/mol
P = 1.3 atm = 131 722.5 Pa

PV = nRT
PV = m*(R/MR)T
m = PV*MR/RT
m = 131 722.5*0.008*32 / (8.314 * 298)
m = 13.61 gr