|
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 disorder of the system
|
|
|
|
|
|
Gibbs free energy change (
G
)
|
thermodynamic property defined in terms of system enthalpy and entropy; all spontaneous processes involve a decrease in
G
|
|
|
|
|
|
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
|
|
|
|
|
|
reversible process
|
process that takes place so slowly as to be capable of reversing direction in response to an infinitesimally small change in conditions; hypothetical construct that can only be approximated by real processes
|
|
|
|
|
|
second law of thermodynamics
|
all spontaneous processes involve an increase in the entropy of the universe
|
|
|
|
|
|
spontaneous change
|
process that takes place without a continuous input of energy from an external source
|
|
|
|
|
|
standard entropy (
S
°)
|
entropy for one mole of a substance at 1 bar pressure; tabulated values are usually determined at 298.15 K
|
|
|
|
|
|
standard entropy change (Δ
S
°)
|
change in entropy for a reaction calculated using the standard entropies
|
|
|
|
|
|
standard free energy change (Δ
G
°)
|
change in free energy for a process occurring under standard conditions (1 bar pressure for gases, 1 M concentration for solutions)
|
|
|
|
|
|
standard free energy of formation
|
change in free energy accompanying the formation of one mole of substance from its elements in their standard states
|
|
|
|
|
|
third law of thermodynamics
|
entropy of a perfect crystal at absolute zero (0 K) is zero
|
|
|
|
|