1. The problem statement, all variables and given/known data The molar energy of a monatomic gas which obeys van der Waals' equation is given by E = (3/2)RT - a/V V volume, T temperature, a is a constant. Initially you have T1 at V1, and the gas expands adiabatically in a vacuum so that you have V2. What is T2? 2. Relevant equations Van der Waals' equation: P = RT/(V - b) - a/V^2 3. The attempt at a solution Q = 0, so dW = dE. dW = -PdV, and I rewrite P in terms of V and T according to van der Waals' equation, then try to rearrange terms so that I can integrate, but I don't think the terms are separable, and I'm beginning to wonder if there is something wrong in my approach. Any help would be appreciated.