Why Do Authors Use γ=γ(P,T) Instead of γ=γ(P,T,V) in Thermodynamics?

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Discussion Overview

The discussion revolves around the representation of the thermal coefficient of pressure, γ, in thermodynamics, specifically why it is often expressed as γ=γ(P,T) rather than γ=γ(P,T,V) or γ=γ(T,V). Participants explore the implications of these different representations and their convenience in calculations.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant defines the thermal coefficient of pressure as γ=1/P(∂P/∂T)_V and questions why it is typically presented as γ=γ(P,T).
  • Another participant notes that since the equation of state relates volume to pressure and temperature (V=V(P,T)), there are effectively only two independent variables.
  • A later reply questions the possibility of expressing γ as γ=γ(T,V) and acknowledges that while it can be done, it may not be as convenient for calculations.

Areas of Agreement / Disagreement

Participants express differing views on the representation of γ, with some supporting the use of γ=γ(P,T) while others consider the alternative γ=γ(T,V) as a valid option, leading to an unresolved discussion on the most appropriate form.

Contextual Notes

The discussion highlights the dependence on the equation of state and the potential implications of choosing different independent variables, but does not resolve the nuances of these dependencies.

LagrangeEuler
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Thermal coefficient of pressure is defined by
\gamma=\frac{1}{P}(\frac{\partial P}{\partial T})_V. Why in books authors uses ##\gamma=\gamma(P,T)## and no ##\gamma=\gamma(P,T,V)##. Could you explain me this. I am sometimes confused with this dependences in thermodynamics.
 
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LagrangeEuler said:
Thermal coefficient of pressure is defined by
\gamma=\frac{1}{P}(\frac{\partial P}{\partial T})_V. Why in books authors uses ##\gamma=\gamma(P,T)## and no ##\gamma=\gamma(P,T,V)##. Could you explain me this. I am sometimes confused with this dependences in thermodynamics.
From the equation of state, V=V(P,T), so there are really only to independent variables.
 
Ok. Thanks. But why not ##\gamma=\gamma(T,V)##?
 
LagrangeEuler said:
Ok. Thanks. But why not ##\gamma=\gamma(T,V)##?
That can be done, but it's not as convenient for calculations.
 
Thanks.
 

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