USE EXCEL to Consider a fluid that obeys the van der Waals equation of state
= − 1 with ≥ .
− 2
Using the reduced variables
= , = , and = ,
and equations (3), (4) and (5) from the attached file, express the van der Waals equation in the form =
( , ). Use this form to prepare a high-quality graph of the compressibility factor
3
== ,
8
versus reduced pressure, , for six isotherms that correspond to values of the reduced temperature
=2.0,1.5,1.3,1.2,1.1,and1.0.
The scale of the axes should be: 0.1 ≤ ≤ 1.1 (y-axis) and 0 ≤ ≤ 7 (x-axis).
Note: the equations contain the reduced volume, . In order to prepare the graph, for a given value
of we vary the volume (or, better, the logarithm of the volume), we calculate the pressure, ,
from the reduced form of the equation of state, and finally we calculate . Then we plot vs
and we repeat for other values of . This is conveniently done using excel.
0 comments