Find thermal capacity of a Van der Waals gas

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SUMMARY

The discussion focuses on determining the heat capacities, \(C_P\) and \(C_V\), of a Van der Waals gas using the provided equations. The main equation discussed is \(C_P - C_V = \frac{R}{1 - \frac{2a(V-b)^2}{RTV^3}}\). Participants emphasize the necessity of knowing the internal energy \(U\) or entropy \(S\) to calculate these capacities accurately. It is concluded that without additional information about the gas, such as its internal energy, the problem remains unsolvable.

PREREQUISITES
  • Understanding of Van der Waals equation of state
  • Knowledge of heat capacity definitions and relationships
  • Familiarity with thermodynamic concepts such as internal energy and entropy
  • Proficiency in calculus for deriving relationships between thermodynamic variables
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  • Research the internal energy of Van der Waals gas from thermodynamics literature
  • Study Mayer's relation for calculating \(C_P\) from \(C_V\)
  • Explore the derivation of heat capacities for ideal gases and their comparison to Van der Waals gases
  • Investigate the implications of molecular degrees of freedom on heat capacities
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Students and professionals in thermodynamics, particularly those studying gas behavior and heat capacity calculations in non-ideal gases.

  • #31
MatinSAR said:
So for showing that ##[\frac {\partial C_V} {\partial V}]_T=0## I can use the link you've sahred ...
So do you see any other problem in my final answer?
Your argument goes like this:
  1. Assume (or prove) that ##C_V## does not depend on the volume
  2. Use the equation of state to derive the rhs of Mayer's relation
  3. Assume ##C_V=\frac32nR##
  4. Insert (3) in Mayer's relation
However step 1 was not needed.
 
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  • #32
pines-demon said:
Your argument goes like this:
  1. Assume (or prove) that ##C_V## does not depend on the volume
  2. Use the equation of state to derive the rhs of Mayer's relation
  3. Assume ##C_V=\frac32nR##
  4. Insert (3) in Mayer's relation
However step 1 was not needed.
Thanks again for your time @pines-demon ...
 
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