570 torr. The ideal gas law is PV = nRT where P = pressure V = volume n = number of moles of gas particles R = Ideal gas constant T = absolute temperature Since the value n, R, and T remain constant for this problem, that indicates that if the volume is doubled, the pressure will be halved. So the new pressure will be 1.50 atm / 2 = 0.750 atm. Now we just need to convert that from atm to torr. 1 atm is equal to 760 torr, so 0.750 atm * 760 torr/atm = 570 torr.