Question

Under what circumstances would you expect a gas to behave significantly differently than predicted by the ideal gas law?

Short answer

The gases deviate from ideal gas behavior at high pressure and low temperature. The ideal gas law tries to describe the behavior of real gases in ideal conditions. But at high pressure or low temperature, it doesn’t give us a clear description of gas behaviors.

Step-by-step solution

Ideal gas

Under high pressure and low temperature, a real gas does not completely obey the ideal gas behavior.

Deviation from the ideal gas

An ideal gas is said to follow the gas laws in all conditions of pressure and temperature. To do so the gas need to follow the kinetic molecular theory. Whereas, a real gas is a gas that does not follow the kinetic molecular theory’s assumption. Fortunately, at the conditions of temperature and pressure that are normally encountered in a laboratory, real gases tend to behave very much like ideal gases.

When a gas is put under very high pressure, its molecules are very close and the empty spaces between the particles are decreased. This means that the volume of the particles themselves is negligible and is less valid.

When a gas is cooled, Kinetic energy is decreased and the particles are moving at a slower speed and the attractive force between them is more prominent. So we can say that a real gas deviates from an ideal gas at high pressure and low temperature.