# Thermodynamics Compressibility Factor

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1. Feb 27, 2017

### Logan McEntire

1. The problem statement, all variables and given/known data
Please consider ethylene at 152oF and 126 atm. Please determine the molar volume (ft3/lbmole) if Z is determined by Corresponding States Theory.

2. Relevant equations
Z=PVm/RmT
Vm= Molar volume
R=Rm/M
M= molecular weight
Rm=1545(ft*lbf)/(lbmol*oR)
Zc=(Pcvc)/(R*Tc)
Tc=283 K
Pc=51.2 Bar
M=28.05 Kg/Kmol
PR=P/Pc
3. The attempt at a solution
I can find Vc but thats not 152 oF and 126 atm.
I don't know Z at these conditions either so I can't use the other equation.

2. Feb 27, 2017

### Staff: Mentor

What is the reduced temperature and the reduced pressure? Do you have a copy of the graph of z as a function of reduced pressure and reduced temperature?

3. Mar 11, 2017

### John Park

I'd imagine that if they say "Z is determined by Corresponding States Theory", that implies it's constant.

4. Mar 11, 2017

### Staff: Mentor

What does this mean? Actually, z is a function of reduced pressure and reduced temperature. Do you know the definition of these quantities?

5. Mar 11, 2017

### John Park

For an ideal gas (admittedly a long way from the critical point) z is constant as a function of pressure. Closer to the critical point in general it varies with pressure, but that doesn't seem to rule out the possibility that it takes its critical value here. How would you use the statement about Corresponding States Theory?

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