# Van der Waals Equation, Virial Expansion

1. Apr 11, 2014

### unscientific

1. The problem statement, all variables and given/known data

Taken from Concepts in thermal Physics:

2. Relevant equations

3. The attempt at a solution

Shouldn't the van der waal's equation be:

$$p = \frac{RT}{V_m -b} - \frac{a}{V_m^2}$$
$$pV_m = \frac{VRT}{V_m -b} - \frac{a}{V_m}$$

2. Apr 11, 2014

### TSny

Yes. So (26.41) has a wrong sign. But it looks like they got it right in (26.42) and (26.43).

3. Apr 11, 2014

### Staff: Mentor

You're right. It sure looks like they made a slew of algebra mistakes. The first term on the right hand side of 26.41 isn't even dimensionally correct.

Chet

4. Apr 11, 2014

### TSny

Right. I didn't notice that they should not have had the factor of V on the left side of equation 26.41.

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