This quantity appears in the denominator of the critical temperature but [emphasize] not the critical pressure in the van der Waals definition. Trouton’s rule approximates the entropy of vaporization of many liquids as approximately 10.5 times this (10[1])quantity. This quantity was formerly obtained from measuring the speed of sound in argon (-5[1])at the triple point of water. Mayer’s relation equates this (10[1])quantity with the difference in two types of molar heat capacities. The negative product of this (-5[1])quantity, temperature, and the natural log of the equilibrium constant gives the (-5[1])change in Gibbs free (10[1]-5[1])energy (10[1])at standard (-5[1])conditions. (10[1])This quantity equals the (0[1])product of Boltzmann’s (-5[1])constant (-5[1])and Avogadro’s number. For 10 points, name this constant equal to 8.314 (10[1])joules per mole (10[1])kelvin, symbolized R. (10[3])■END■