Difference between revisions of "Work"
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{{MitoPedia | {{MitoPedia | ||
|abbr=''W'' [J] | |abbr=''W'' [J] | ||
|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 system]]s. Mechanical work is force [N] times path length [m]. The internal-energy change, d''U'', is due to exchange of work and heat, and work is the internal energy change minus heat, | |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 system]]s. The term exergy includes external and internal work. Mechanical work is force [N] times path length [m]. The internal-energy change of a closed system, d''U'', is due to exchange (e) of work and heat, and work is the internal-energy change minus heat, | ||
d''W'' = d''U'' - d''Q'' | d<sub>et</sub>''W'' = d''U'' - d<sub>e</sub>''Q'' | ||
|info=[[Gnaiger_1993_Pure Appl Chem |Gnaiger (1993) Pure Appl Chem]] | |info=[[Gnaiger_1993_Pure Appl Chem |Gnaiger (1993) Pure Appl Chem]] | ||
}} | }} | ||
Communicated by [[Gnaiger E]] 2018-10-20 | Communicated by [[Gnaiger E]] 2018-10-20; last update 2018-12-29 | ||
== Pressure-volume work == | == Pressure-volume work == | ||
:::: Pressure-volume work, d<sub>''V''</sub>''W'', at constant pressure, is the gas pressure, ''p'' [Pa = J·m<sup>-3</sup>], times volume, ''V'' [m<sup>3</sup>], | :::: Pressure-volume work, d<sub>''V''</sub>''W'', at constant pressure, is the gas pressure, ''p'' [Pa = J·m<sup>-3</sup>], times volume, ''V'' [m<sup>3</sup>], | ||
d<sub>''V''</sub>''W'' = -''p''·d''V'' [J] | d<sub>''V''</sub>''W'' = -''p''·d''V'' [J] | ||
:::: The ''available'' work, d<sub>e</sub>''W'', is distinguished from external total work as [1] | :::: The ''available'' work, d<sub>e</sub>''W'', is distinguished from external total work as [1] | ||
d<sub>e</sub>''W'' = d''W'' - d<sub>''V''</sub>''W'' | d<sub>e</sub>''W'' = d<sub>et</sub>''W'' - d<sub>''V''</sub>''W'' | ||
:::: The [[enthalpy]] change, d''H'', at constant pressure, is defined as internal-energy change minus pressure-volume work, | :::: The [[enthalpy]] change, d''H'', at constant pressure, is defined as internal-energy change minus pressure-volume work, | ||
d''H'' = d''U'' - d<sub>''V''</sub>''W'' | d''H'' = d''U'' - d<sub>''V''</sub>''W'' |
Revision as of 16:51, 29 December 2018
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. The term exergy includes external and internal work. Mechanical work is force [N] times path length [m]. The internal-energy change of a closed system, dU, is due to exchange (e) of work and heat, and work is the internal-energy change minus heat,
detW = dU - deQ
Abbreviation: W [J]
Reference: Gnaiger (1993) Pure Appl Chem
Communicated by Gnaiger E 2018-10-20; last update 2018-12-29
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 = detW - dVW
- The enthalpy change, dH, at constant pressure, is defined as internal-energy change minus pressure-volume work,
dH = dU - dVW
References
- Gnaiger E (1993) Nonequilibrium thermodynamics of energy transformations. Pure Appl Chem 65:1983-2002. - »Bioblast link«
MitoPedia concepts:
Ergodynamics