According to the ideal gas law, a 1.074 mol sample of oxygen gas in a 1.746 l container at 267.6 k should exert a pressure of 13.51 atm. what is the percent difference between the pressure calculated using the van der waals' equation and the ideal pressure? for o2 gas, a = 1.360 l2atm/mol2 and b = 3.183×10-2 l/mol.