Equilibrium partial pressures

1. Nov 4, 2007

wingsb2

It's been a while since I've done any equilibrium problems - especially ones at constant temperature so some help would be appreciated.

I have a dissocation reaction A_2 <----> 2A. I am told that at temperature T and pressure P1 = 1atm, there are twice as many moles of A_2 molecules as there are of A atoms. Then the mixture is expanded at constant temperature to 4 times the initial volume. I need to find the equilibrium partial pressures of A_2 and A and the total pressure P2.