Units of energy Units of energy Because energy is defined via work, the SI unit for energy is the same as the unit of work – the joule (J), named in honor of James Prescott Joule and his experiments on the mechanical equivalent of heat. In slightly more fundamental terms, 1 joule is equal to 1 newton metre and, in terms of SI base units An energy unit that is used in atomic physics, particle physics and high energy physics is the electronvolt (eV). One eV is equivalent to 1.60217653×10 J. In spectroscopy the unit cm = 0.000123986 eV is used to represent
Gibbs free energy we add the qualification that it is the energy available for "non-volume" work. (An analogous, but slightly different, meaning of "free" applies in conjunction with the Helmholtz free energy, for systems at constant temperature). However, an increasing number of books and journal articles do not include the attachment "free", referring to "G" as simply "Gibbs energy". This is the result of a 1988 IUPAC meeting to set unified terminologies for the international scientific community, in which the adjective "free" was supposedly banished. This standard, however, has not yet been universally adopted. The quantity called "free energy" is a more advanced