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Work

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Revision as of 17:54, 28 December 2018 by Gnaiger Erich (talk | contribs)


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Work

Description

Work [J] is a specific form of energy, called exergy, performed by a closed or open system on its surroundings (the environment). This is the definition of external work, which is zero in isolated systems. Mechanical work is force [N] times path length [m]. The internal-energy change, dU, is due to exchange of work and heat, and work is the internal energy change minus heat,

dW = dU - dQ

Abbreviation: W [J]

Reference: Gnaiger (1993) Pure Appl Chem

Communicated by Gnaiger E 2018-10-20

Pressure-volume work

Pressure-volume work, dVW, at constant pressure, is the gas pressure, p [Pa = J·m-3], times volume, V [m3],
dVW = -p·dV [J]
The available work, deW, is distinguished from external total work as [1]
deW = dW - dVW
The enthalpy change, dH, at constant pressure, is defined as internal-energy change minus pressure-volume work,
dH = dU - dVW

References

  1. Gnaiger E (1993) Nonequilibrium thermodynamics of energy transformations. Pure Appl Chem 65:1983-2002. - »Bioblast link«


MitoPedia concepts: Ergodynamics