My EK book says Vreal>Videal because ideal gas molecules have no volume and thus must be less than the volumes of real gas molecules, where as TBR says Vreal<Videal because real gases experience intermolecular forces pulling them closer together than ideal gases. Which is it?
Thanks !!
Real Gas molecules DO have volume, however, when using the Ideal Gas Law, a lot of assumptions are made. First, it's assumed that the volume of a gas(es) is negligible when the pressure is low (lots of free volume) and temperature is high (lots of kinetic energy). The gas molecules are free to fly all over the place.
So for example when a problem tells you that a certain type of gas is occupying a container of "X" volume, it doesn't take into account the net volume of the gas (because it's assumed to behave ideally ...unless they state otherwise).
However, for a non-ideal gas, the "true" volume would be "Total Vol. = Volume of Container - Volume of Gases." Therefore, Vreal would LESS than Videal (under non-ideal conditions).
Also, intermolecular forces (attraction / repulsion ) of gas molecules can affect the Pressure within a container. If two different gases attract each other than Preal < Pideal because they hit the container wall less. However, if the intermolecular forces repel each other, they hit the container wall more often so Preal > Pideal.
This is the whole idea behind Van der Waals equation.
I hope this helps.