Calculating isothermal copressibility and expansion coefficient

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SUMMARY

This discussion focuses on calculating the isothermal compressibility and expansion coefficient of a Van der Waals gas. The relevant equations are isothermal compressibility \( K = \frac{-1}{V} \left( \frac{dv}{dp} \right)_T \) and isothermal expansion coefficient \( \alpha = \frac{1}{v} \left( \frac{dv}{dt} \right)_P \). Participants emphasize the importance of using the Van der Waals equation of state \( (p + \frac{a}{V^2})(V - b) = RT \) to derive the necessary partial derivatives. The discussion also highlights the application of Euler's chain relation to establish the relationship \( K_R = \alpha(V_m - b) \).

PREREQUISITES
  • Understanding of Van der Waals equation of state
  • Knowledge of partial derivatives in thermodynamics
  • Familiarity with isothermal processes
  • Basic principles of thermodynamic coefficients
NEXT STEPS
  • Study the derivation of the Van der Waals equation of state
  • Learn about the application of Euler's chain relation in thermodynamics
  • Explore the implications of isothermal compressibility in real gases
  • Investigate the relationship between thermodynamic properties and phase behavior
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Students and professionals in thermodynamics, particularly those studying gas behavior and properties, as well as researchers focusing on real gas equations and their applications.

Zcuttlefish
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Homework Statement


Calculate the isothermal compressibility and the expansion coefficient of a van der waals gas. Then show using Euler's chain relation that KR = alpha(Vm-b)


Homework Equations


isothermal compressibility K = (-1/V) (dv/dp)t
isothermal expansion alpha= (1/v)(dv/dt)p


The Attempt at a Solution


I realize it has to do with partial derivatives. But beyond this I'm lost.
 
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Hi Zcuttlefish, welcome to PF!:smile:

Hint: You might start by looking up the equation of state for a Van Der Waals gas!:wink:
 
I did (p+ a/V2)(v-b) = RT
(not including n because it should be constant)

my answer for dv/dp ended up looking like
Then i used the product rule and took the derivative dv/dp of the terms. I'm still unsure of why or if I've even gotten closer to the answer.

V3(v-b)/(2a(v-b)2-RTV3)
I seem to be missing an R on top.
 

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