Entropy ( S ) is a state function that can be related to the number of microstates for a system (the number of ways the system can be arranged) and to the ratio of reversible heat to kelvin temperature. A spontaneous process occurs without the need for a continual input of energy from some external source, while a nonspontaneous process requires such.

Systems undergoing a spontaneous process may or may not experience a gain or loss of energy, but they will experience a change in the way matter and/or energy is distributed within the system It may be interpreted as a measure of the dispersal or distribution of matter and/or energy in a system, and it is often described as representing the “disorder” of the system

entropy ( S ) — state function that is a measure of the matter and/or energy dispersal within a system, determined by the number of system microstates; often described as a measure of the…. microstate — possible configuration or arrangement of matter and energy within a system. nonspontaneous process — process that requires continual input of energy from an external source. system — heated and when solutions form.