Posted by Hannah on .
According to the ideal gas law a 9.03 sample of oxygen gas in a 0.8112 container at 499k should exert a pressure of 456atm. By what % does the pressure calculated using van der waals equation differ from the ideal pressure?
For O2 gas a=1.36 L^2atm/mol2 and b=3.18e2
Hint: %diff= 100 X (P ideal  P van der waal) / P ideal
I know that van der waals equation is
(P + a [n/v]^2) (vbn) = nRT but I have no idea how to use this and my textbook does not give any examples. Thank you for your help!

Chemistry 
DrBob222,
First, you omitted the units on the 9.03 WHAT in a 0.8112 WHAT container. I'm confused because you are confused. There is nothing here that you need an idea about. You have a and b, R, T, and n. Solve for P by van d equation, then use the usual PV = nRT and solve for P. Then follow the hint in the problem which tells you how to solve for the % difference.