Finding the equations of state via the fundamental relation

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SUMMARY

The discussion focuses on deriving equations of state using the fundamental relation in thermodynamics, specifically through entropy representation. Key equations include the partial derivatives of entropy with respect to internal energy and volume, expressed as $$\frac{\partial S}{\partial u}\Bigr|_{v} = \frac{1}{T}$$ and $$\frac{\partial S}{\partial v}\Bigr|_{u} = \frac{-P}{T}$$. The user attempts to manipulate these equations to express entropy in terms of specific variables and seeks confirmation on the correctness of their approach before proceeding further. The challenge lies in understanding the implications of homogeneity in these functions.

PREREQUISITES
  • Understanding of thermodynamic concepts, particularly entropy and its derivatives.
  • Familiarity with equations of state in thermodynamics.
  • Knowledge of homogeneous functions and their properties.
  • Proficiency in manipulating mathematical equations involving partial derivatives.
NEXT STEPS
  • Study the properties of homogeneous functions in thermodynamics.
  • Explore the derivation of equations of state from fundamental thermodynamic relations.
  • Learn about the implications of entropy in statistical mechanics.
  • Investigate the application of the Maxwell relations in thermodynamic systems.
USEFUL FOR

Students and researchers in thermodynamics, particularly those focusing on statistical mechanics and the derivation of equations of state. This discussion is beneficial for anyone looking to deepen their understanding of entropy and its role in thermodynamic equations.

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Homework Statement



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Homework Equations



$$\frac{\partial S}{\partial u}\Bigr|_{v} = \frac{1}{T}$$
$$\frac{\partial S}{\partial v}\Bigr|_{u} = \frac{-P}{T}$$[/B]

The Attempt at a Solution



a.) $$\frac{S}{R} = \frac{UV}{N} - \frac{N^3}{UV}$$ $$\frac{S}{R} = \frac{UV}{N} - \frac{N}{uv}$$ $$ \frac{S}{NR} = \frac{UV}{N^2} - \frac{1}{uv} $$ $$\frac{s}{R} = uv - \frac{1}{uv}$$ where ##s = \frac{S}{N}##, ##u = \frac{U}{N}##, and ##v = \frac{V}{N}##.

Equations of state(in entropy representation):

$$\frac{\partial S}{\partial u}\Bigr|_{v} = \frac{1}{T} = R(v + \frac{1}{uv^2}) $$

$$\frac{\partial S}{\partial v}\Bigr|_{u} = \frac{P}{T} = R(u + \frac{1}{vu^2}) $$

And this is where I get stuck; when I try and multiply ##u## and ##v## by a constant, i.e. ##\lambda v + \frac{1}{\lambda u (\lambda v)^2}##, this is obviously not homogeneous of order zero. I have an idea about how to continue the rest of the parts, but I want to be sure that the first one is correct be for I move on.
My values for ##P## and ##T## in the entropy representation seem right, maybe I'm not quite understanding what a homogeneous function actually is. Any help is appreciated.[/B]
 
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