For 10 points, name these theoretical substances that consist of randomly moving point particles unaffected by intermolecular forces.
The ratio between the volume of these entities and the volume of their counterparts defines the compressibility factor, and the Sackur-Tetrode equation solves for the entropy of a specific type of these substances. A molecule of these substances has an average kinetic energy of three-halves times Boltzmann's constant times the absolute temperature. Johannes van der Waals generalized these substances' namesake equation by accounting for differences in pressure and volume; that law can be written as "PV equals nRT." For 10 points, name these theoretical substances that consist of randomly moving point particles unaffected by intermolecular forces.
The ratio between the volume of these entities and the volume of their counterparts defines the compressibility factor, and the Sackur-Tetrode equation solves for the entropy of a specific type of these substances.
ideal gases [prompt on "gases"]