In thermodynamics, what does the entropy change of a reaction, $\Delta S$, describe?

• A. The heat absorbed by the system at constant pressure, $\Delta H$
• B. The change in average kinetic energy of the molecules (i.e., the temperature change)
• C. The change in the dispersal of energy and the number of accessible microstates as reactants form products
• D. The maximum useful work obtainable from the reaction at constant temperature and pressure, $\Delta G$

Answer: (C)