Question

What weight of ethane is contained in a gas cylinder of 1.0 ft3 in volume if the gas is at 100oF and 2000 psig? Use the compressibility factor method. Critical properties of Ethane (C2H6) are: Tc= 305.4 K, Pc=48.2 atm. Molecular weight of ethane is: 30.07 g / g-mol. Atmospheric pressure is 14.696 psi.

Answer 1

Apply

PV = ZnRT

find n

n = PV/(ZRT)

change all to SI units

V = 1 ft^3 = 0.0283168 m3

T = 100°f = 310.928 K

P = 2000 psig = 2014.7 psia = 137.092203 atm

Find

Tr = T/Tc = (310.928/305.4 ) = 1.01810

Pr = P/Pc = (137.092203/48.2) = 2.84

Find in Z table:

Z = 0.42 approx

Then

n = PV/(ZRT) = (137.092203*101325)(0.0283168 )/(0.42*8.314*0.0283168 ) = 3978048.34902 mol

mass = mol*MW = 3978048.34902*30.07 = 119619913.855 g

mass = 119619.913 kg of ethane

this is due to the high pressure!