#Variable Declaration
m = 1.0 #Mass of Methane, kg
T = 230 #Temeprature of Methane, K
P = 68.0 #Pressure, bar
Tc = 190.56 #Critical Temeprature of Methane
Pc = 45.99 #Critical Pressure of Methane
R = 0.08314 #Ideal Gas Constant, L.bar/(mol.K)
M = 16.04 #Molecular wt of Methane
#Calcualtions
Tr = T/Tc
Pr = P/Pc
z = 0.63 #Methane compressibility factor
n = m*1e3/M
V = z*n*R*T/P
Vig = n*R*T/P
DV = (V - Vig)/V
#Results
print '(V-Videal) %4.2f L'%(V-Vig)
print 'Percentage error %5.2f'%(DV*100)