ABSTRACT
Entropy is defined by the Second Law of Thermodynamics and is representative of the arrangement of particles (“order”) in the system or the distribution of thermal energy in “microstates” in the system. It is a critical part of chemical thermodynamics and defines the natural direction of changes in the Universe. Matter consists of atoms and molecules that have discrete energy states (or microstates), that also have degrees of freedom (such as translational, rotational, and vibrational energies, dependent on the state of matter, size of molecule, bonding, and types of atoms in the molecule). But many substances, such as amorphous solids (glasses), cannot form a single uniform state at 0K and have “residual entropy” or non-zero values for S at 0K. Other factors that can result in residual entropy are crystalline defects, alterations in structure due to resonance structures or isomers, misalignment of net dipoles, and the like.
