Equations of state -- Partial derivatives & Expansivity

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SUMMARY

The coefficient of volume expansion (β) can be expressed as β = -1/ρ (∂ρ/∂T) under constant pressure conditions. The relationship between density (ρ) and volume (v) is defined as 1/v = ρ. To derive the expression for β, one can substitute ρ for 1/v and apply the chain rule of derivatives, leading to the conclusion that β = ρ(∂v/∂T). This discussion emphasizes the importance of understanding partial derivatives in thermodynamic equations.

PREREQUISITES
  • Understanding of thermodynamic principles
  • Familiarity with partial derivatives
  • Knowledge of the relationship between density and volume
  • Basic calculus skills, particularly the chain rule
NEXT STEPS
  • Study the application of the chain rule in thermodynamics
  • Explore the derivation of other thermodynamic coefficients
  • Learn about the implications of volume expansion in materials science
  • Investigate the role of pressure in thermodynamic equations
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Students studying thermodynamics, physicists, and engineers interested in the properties of materials under varying temperature and pressure conditions.

Mia_S
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Homework Statement



Show that the coefficient of volume expansion can be expressed as

β= -1÷ρ (∂ρ÷∂T) keeping P (pressure) constant
Where rho is the density
T is Temperature

Homework Equations


1/v =ρ
β= 1/v (∂v÷∂T) keeping P (pressure ) constant

The Attempt at a Solution


I started with the original equation (β= 1/v (∂v÷∂T) ) ,substituted ρ for 1/v and got stuck . What should I do next? What's the solution?

Thank you!
 
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Mia_S said:
substituted ρ for 1/v and got stuck
"Stuck" where?
 
Bystander said:
"Stuck" where?
Here, β= ρ(∂v÷∂T)
 
You're using "ρ = 1/v," so what's the next step?
 
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Bystander said:
You're using "ρ = 1/v," so what's the next step?
I don't know :( ...Should I change the partial derivative to 1/(∂T÷∂v) ?
 
May I suggest you use the chain rule of derivatives since V=1/rho=(rho)^-1. Take the derivative of the outside function times the derivative of the inside.
 
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If v = 1/ρ, then, in terms of ρ and dρ, dv = ??

Chet
 
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I got it! Thank you :)
 

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