Enthalpy: Difference between revisions
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'''Enthalpy''' (<math>H</math>) <ref>[http://www.dwc.knaw.nl/DL/publications/PU00013601.pdf J. P. Dalton "Researches on the Joule-Kelvin effect, especially at low temperatures. I. Calculations for hydrogen", KNAW Proceedings '''11''' pp. 863-873 (1909)]</ref><ref>[http://dx.doi.org/10.1021/ed079p697 Irmgard K. Howard "H Is for Enthalpy, Thanks to Heike Kamerlingh Onnes and Alfred W. Porter", Journal of Chemical Education '''79''' pp. 697-698 (2002)]</ref> is defined as: | |||
:<math> | :<math>H:=U+pV</math> | ||
where <math>U</math> is the [[internal energy]], <math>p</math> is the [[pressure]], <math>V</math> is the volume. | |||
<math>pV</math> is a ''conjugate pair''. The differential of this function is | |||
:<math>\left.dH\right.=dU+pdV+Vdp</math> | :<math>\left.dH\right.=dU+pdV+Vdp</math> | ||
| Line 15: | Line 16: | ||
:<math>\left.dH\right.=TdS +Vdp</math> | :<math>\left.dH\right.=TdS +Vdp</math> | ||
For | For <math>H(S,p)</math> we have the following ''total differential'' | ||
:<math>dH=\left(\frac{\partial H}{\partial S}\right)_p dS + \left(\frac{\partial H}{\partial p}\right)_S dp</math> | :<math>dH=\left(\frac{\partial H}{\partial S}\right)_p dS + \left(\frac{\partial H}{\partial p}\right)_S dp</math> | ||
==References== | |||
<references/> | |||
[[Category: Classical thermodynamics]] | [[Category: Classical thermodynamics]] | ||
Latest revision as of 18:50, 20 February 2015
Enthalpy () [1][2] is defined as:
where is the internal energy, is the pressure, is the volume. is a conjugate pair. The differential of this function is
From the Second law of thermodynamics one obtains
thus we arrive at
For we have the following total differential
References[edit]
- ↑ J. P. Dalton "Researches on the Joule-Kelvin effect, especially at low temperatures. I. Calculations for hydrogen", KNAW Proceedings 11 pp. 863-873 (1909)
- ↑ Irmgard K. Howard "H Is for Enthalpy, Thanks to Heike Kamerlingh Onnes and Alfred W. Porter", Journal of Chemical Education 79 pp. 697-698 (2002)