Molar Free Energy of an Ideal Gas at Temperature T and Pressure P

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SUMMARY

The discussion focuses on deriving the equation for the change in free energy, ΔGmixing, when mixing ideal gases at the same temperature (T) and pressure (P). The key equation presented is ΔGmixing = nRT∑(xi)ln(xi), where xi represents the mole fraction of each gas. Additionally, the relationship (∂/∂T(G/T))p = -H/(TxT) is highlighted, emphasizing the connection between free energy and enthalpy. The molar free energy of a pure ideal gas at temperature T and pressure P is also addressed, specifically in relation to its standard state at 1 atm.

PREREQUISITES
  • Understanding of thermodynamic concepts, specifically free energy and enthalpy.
  • Familiarity with the ideal gas law and its applications.
  • Knowledge of mole fractions and their significance in mixtures.
  • Basic calculus, particularly partial derivatives in thermodynamics.
NEXT STEPS
  • Study the derivation of the Gibbs free energy equation in detail.
  • Explore the implications of mixing ideal gases on thermodynamic properties.
  • Learn about the standard state conditions for gases and their impact on free energy calculations.
  • Investigate the role of temperature and pressure in determining the molar free energy of gases.
USEFUL FOR

Students and professionals in chemistry and chemical engineering, particularly those focusing on thermodynamics and gas behavior in mixtures.

ChristineMarie
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Homework Statement


Derive an equation for the change in free energy, ΔGmixing, when ideal gases with the same temperature and pressure, are mixed.

Homework Equations


ΔGmixing = nRT∑(xi)ln(xi)
(∂/∂T(G/T))p = -H/(TxT)

The Attempt at a Solution


Pi = xiPi*
μi = Gi,m
μ = (∂G/∂n) at constant T and P
μ = (∂[nGm]/∂n) = Gm
 
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ChristineMarie said:

Homework Statement


Derive an equation for the change in free energy, ΔGmixing, when ideal gases with the same temperature and pressure, are mixed.

Homework Equations


ΔGmixing = nRT∑(xi)ln(xi)
(∂/∂T(G/T))p = -H/(TxT)

The Attempt at a Solution


Pi = xiPi*
μi = Gi,m
μ = (∂G/∂n) at constant T and P
μ = (∂[nGm]/∂n) = Gm
If ##\mu^0(T)## represents the molar free energy of an ideal gas at temperature T and 1 atm, what is the molar free energy of a pure (unmixed) ideal gas at temperature T and pressure P (P in atm)?

Chet
 
Last edited:

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