Answer: (a) m=7.64kg (b)m=7.64kg
Explanation: (a) Calculating the mass of nitrogen using the ideal gas model:
P.V=n.R.T
Note: as pressure is in Pascal and volume is in m³, the constant R will be 8,31J/K.mol.
Totransform kPa in Pa: P=1356kPa → P=1356.10³ Pa
To use the temperature, it has to be in Kelvin: T=2718°C → T = 2718 + 273 = 2991K
P.V=n.R.T
n=(P.V) / (R.T)
n= (1356.10³. 0.5) / (8.31.2991)
n= 27,28 mols
For nitrogen, 1 mol = 28,014 g so m=764,22g or, in this case, m=764220kg.
(b) To calculate the mass with the compressibility chart, use a compatibility factor Z, which is Z=(p.v) / (R.T). If the factor Z=1, the gas behaves ideally.
This means that, in general, gases behaves almost ideally. So, in this case, calculating the mass of nitrogen by the ideal gas law or the Z factor will result in the same quantity.