Gibbs Free Energy: Explained & Explored

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Discussion Overview

The discussion revolves around the concept of Gibbs free energy, exploring its definition, applications, and significance in thermodynamics, particularly in isothermal and isobaric processes. Participants seek to clarify their understanding and explore different perspectives on the topic.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions the understanding of Gibbs energy, suggesting it may represent the work obtainable from a system at fixed temperature and pressure.
  • Another participant provides a definition of Gibbs free energy as G = H - TS, noting its use in isothermal and isobaric processes, and contrasts it with Helmholtz free energy, which is more relevant for isothermal and isochoric processes.
  • A third participant acknowledges the previous explanation with a simple thanks.
  • Further, a participant emphasizes the importance of Gibbs free energy in open systems or chemical reactions, mentioning that it can be expressed in terms of chemical potentials and the extensive nature of particle numbers.

Areas of Agreement / Disagreement

The discussion reflects a lack of consensus on the fundamental understanding of Gibbs free energy, with multiple viewpoints presented regarding its definition and applications. Some participants provide clarifications while others express uncertainty.

Contextual Notes

Participants have not fully resolved the implications of Gibbs free energy in various contexts, such as its role in spontaneous processes or its relationship with Helmholtz free energy. There is also a mention of varying particle numbers and their impact on the concept, which remains to be explored further.

cragar
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I don't think I completely understand what Gibbs energy is, Is it the work you can get out of a system at fixed Temperature and pressure. Does anyone have another angle on it cause It seems weird to me.
 
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The Gibbs free energy is the total energy available to a system, G = H-TS, and is used instead of other free energies such as the Helmholtz free energy (I think there are others as well) when the system undergoes isothermal and isobaric processes. The Helmholtz free energy is more applicable for isothermal and isochoric processes.

Processes that result in a change in the Gibbs free energy ΔG = ΔH-TΔS are classified as "spontaneous" or not depending on the sign of ΔG.
 
ok thanks for your answer.
 
Gibbs free energy is especially important once varying particle numbers are considered, i.e. open systems or chemical ractions. The reason is that of the natural variables T,p, {N_i} only on the particle numbers N_i are extensive variables. By the theorem on homogeneous functions,
G=\sum_i N_i \mu_i i.e. it can be expressed in terms of the chemical potentials of the components.
 

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