A sample of 3.90 moles of oxygen gas, O2, occupies a volume of 6.30 L at a temperature of 21°C.
(a) Calculate the pressure of the gas using the ideal gas equation.
(b) Calculate the pressure of the gas using the van der Waals equation. (The van der Waals constants for O2 are a = 1.360 atm·L2/mol2 and b = 0.03183 L/mol.)