Which estimate do you believe is the most accurate and why?

Estimate the molar volume (in cm3/mol) of superheated butane at 393.2 K and 38 bar using the following methods:

A) Ideal Gas Law.
B) Using Virial EOS (Z = 1 + BP/R/T)…getting B from correlations
C) Using Pitzer expression for Z using the Lee-Kessler approach


A) Using the Ideal Gas equation:









The best estimate would be the Lee-Kesler method. Ideal Gas is not a good model because the butane is a high pressure. Virial is not a good estimate because these conditions for butane are not in the linear region of the model, as indicated by the check below:



However, for butane at these conditions:

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What will be an ideal response?

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