# Virial expansion of van der Waals equation

1. Sep 13, 2009

### winterwind

1. The problem statement, all variables and given/known data
Express the van der Waals equation of state as a virial expansion in powers of 1/Vm and obtain expressions for B and C in terms of the parameters a and b. The expansion you will need is

(1-x)-1 = 1 + x + x2 + ...

Measurements on argon gave B = -2.17 cm3 mol-1 and C = 1200 cm6 mol-2 for the virial coefficients at 273 K. What are the values of a and b in the corresponding van der Waals equation of state?

2. Relevant equations
van der Waals equation: p = nRT/(V-nb) - a(n/V)2

3. The attempt at a solution
Not sure how to approach this...

2. Sep 14, 2009

### Staff: Mentor

$$V-nb = V(1-\frac{nb}{V})$$

and now you can treat (1-nb/V) as (1-x).

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