The derivation of the ideal gas equation employs two assumptions that are invalid for real gas molecules. First, the equation assumes that the molecules of the gas have no volume, which is not true for real molecules. Since the molecules will have some physical volume, the volume that the gas molecules occupy will be increased by the volume that the molecules occupy at rest. In addition, the equation ignores any interactions among the molecules. However, such interactions were first observed in the 19th century by J. D. van der Waals. He realized that, because of the intermolecular forces in the gas, there is a small but measurable attraction among the molecules, which will reduce the pressure of the gas on the walls of the container. To correct for these two deviations from an ideal gas, the van der Waals equation gives (p+an2V2)(V−nb)=nRT,

where a and b are empirical constants, which are different for different gasses.

a. Find the pressure pideal of the gas using the ideal gas equation in this case. Express your answer numerically in pascals.
b. Find the pressure pvdW of the gas at this new volume using the van der Waals equation. Express your answer numerically in pascals.