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