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The state of a thermodynamic system is specified by a number of extensive quantities, the most familiar of which are volume, internal energy, and the amount of each constituent particle (particle numbers). Extensive parameters are properties of the entire system, as contrasted with intensive parameters which can be defined at a single point ...
In thermodynamics, the thermodynamic free energy is one of the state functions of a thermodynamic system. The change in the free energy is the maximum amount of work that the system can perform in a process at constant temperature , and its sign indicates whether the process is thermodynamically favorable or forbidden.
The first law of thermodynamics is essentially a definition of heat, i.e. heat is the change in the internal energy of a system that is not caused by a change of the external parameters of the system. However, the second law of thermodynamics is not a defining relation for the entropy.
In thermodynamics, a change in the thermodynamic state of a system and all of its surroundings cannot be precisely restored to its initial state by infinitesimal changes in some property of the system without expenditure of energy. A system that undergoes an irreversible process may still be capable of returning to its initial state.
The central concept of thermodynamics is that of energy, the ability to do work. By the First Law, the total energy of a system and its surroundings is conserved. Energy may be transferred into a system by heating, compression, or addition of matter, and extracted from a system by cooling, expansion, or extraction of matter.
Informally, however, a difference in the energy of a system that occurs solely because of a difference in its temperature is commonly called heat, and the energy that flows across a boundary as a result of a temperature difference is "heat". Altitude (or elevation) is usually not a thermodynamic property.
Its important to note that the fourth reaction in the series is an inverted homolytic bond cleavage stated in terms of free energy. The chemical transformation for the associated -ΔG˚ is the same it would be for a bond dissociation energy (BDE). However, the -ΔG˚ is not a BDE, since BDE are by definition stated in terms of enthalpy (ΔH˚).
In thermodynamics, the Helmholtz free energy (or Helmholtz energy) is a thermodynamic potential that measures the useful work obtainable from a closed thermodynamic system at a constant temperature . The change in the Helmholtz energy during a process is equal to the maximum amount of work that the system can perform in a thermodynamic process ...