What is an essential condition in the definition of an ideal gas?

An ideal gas is defined under conditions that allow it to behave according to the ideal gas law, which states that the pressure, volume, and temperature of a gas are related in a predictable manner. The essential condition for a gas to approximate ideal gas behavior is found when it is at high temperatures and low pressures.

At high temperatures, the kinetic energy of the gas molecules increases, allowing them to overcome intermolecular forces that might otherwise cause deviations from ideal behavior. Additionally, at low pressures, gas molecules have greater distances between them, which minimizes interactions and the volume occupied by the gas can be treated as the volume of the container. These considerations lead the gas to behave more ideally according to the assumptions of the kinetic molecular theory, where interactions between gas molecules are negligible, and the size of the gas molecules themselves is also negligible compared to the space between them.

In contrast, conditions of low temperature and high pressure can cause gas molecules to become more closely packed, affecting their behavior due to intermolecular forces and the volume occupied by the molecules themselves, which deviates from ideal behavior.