Question

Which of the following statements is true for real gases?
Choose all that apply.

As molecules increase in size, deviations from ideal behavior become more apparent at relatively low pressures.

The volume occupied by the molecules can cause a decrease in pressure compared to the ideal gas.

As molecules increase in size, deviations from ideal behavior become more apparent at relatively high pressures.

The volume occupied by the molecules can cause an increase in pressure compared to the ideal gas.

Answer 1

The volume occupied by the molecules can cause a decrease in pressure compared to the ideal gas

and

As molecules increase in size, deviations from ideal behavior become more apparent at relatively high pressures.

These two are true for real gases.

Real gas molecules have a volume and occupy space. Also at relatively high pressures, the occupied space becomes a significant fraction of the total volume available to the gas sample. A significant decrease in the volume in which the molecules can move about causes an increase in pressure.

There are attractive forces between real gas molecules. When they are important, the attractive forces cause a decrease in gas pressure. At relatively low temperatures, the kinetic energy of the molecules is no longer able to overcome the attractive forces, and a decrease in gas pressure relative to the ideal gas may be observed.