Under what conditions do real gases behave most like ideal gases?

Real gases behave most like ideal gases under conditions of high temperatures and low pressures. At high temperatures, the kinetic energy of the gas molecules increases, which means that they move more rapidly and have less tendency to interact with one another. This limits the effects of intermolecular forces that cause deviations from ideal behavior.

Additionally, at low pressures, the volume of the gas is large relative to the number of molecules present, which means that gas molecules are farther apart. This reduces the impact that molecular attractions and repulsions have, making it easier to assume that gas particles are non-interacting point particles as described in the ideal gas law.

In contrast, at high pressures, gas molecules are forced closer together which increases the influence of intermolecular forces, and at low temperatures, the gas molecules have reduced kinetic energy, leading them to behave more like liquids rather than gases. These conditions cause greater deviations from ideal behavior. Therefore, high temperatures combined with low pressures create an environment in which real gases can approach ideal behavior.