This quantity equals the negative partial derivative of the grand potential with respect to temperature. Ignoring the indistinguishability of particles leads to a non-extensive (10[1])form of this quantity in the Gibbs paradox. Like temperature, the Carnot cycle contains two steps in which this (10[1])quantity (-5[1])is constant. This quantity was defined as proportional to the natural logarithm of the number of microstates by Ludwig Boltzmann. (-5[1])The “arrow of time” is defined because this quantity is non-decreasing (10[1])for isolated systems by the Second Law of Thermodynamics. For 10 (10[2])points, (10[1])name this quantity that is informally the amount of (10[1])disorder in a system. ■END■