# Van der waals gas

1. ### ja87

2
i have to plot isotherms using the van der waals gas theory. i am using Maple to do this but no matter how many differant equations i use i cannot get the graphs to look right. it should look like a 1/x curve but with a sharpe trough in it, but all can get is a graph that looks like a normal 1/x curve. does anyone know the equation i should use to give me the curve of pressure against volume for differant values of temperature.

2. ### Gokul43201

11,141
Staff Emeritus
1. Henceforth, post such questions in the Homework & Coursework subforums.
2. Write down the equation you are using to plot the isotherms
3. What values have you assigned to the coefficients, b and a?
4. You may simply be looking at the isotherms above the critical temperature. Have you chosen values of T that are very small?