A constant characterizing these substances equals the difference between two types of heat capacity, per Mayer’s relation. These substances do not change temperature while undergoing a Joule expansion. A fugacity coefficient of 1 characterizes these substances, which (-5[1])have a value of 0 for the “b” coefficient measuring excluded volume in the van der Waals equation. Avogadro’s number times the Boltzmann constant equals a constant named for these substances, which are typically assumed to have no intermolecular forces. For 10 points, 8.314 joules per mole-kelvin is the value of a constant named for what substances, (10[1])governed by the equation “PV equals nRT”? ■END■