Determine Enthelpy, Entropy, and Chemical Potential

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Discussion Overview

The discussion revolves around a homework problem involving the determination of Enthalpy, Entropy, and Chemical Potential for an isothermal transition of nitrogen (N2) at a constant temperature of 700K, with specified pressures. Participants explore how to approach the problem using only provided Cp data without employing any equations of state.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant states the problem requirements and constraints, emphasizing the use of Cp data and the need to determine thermodynamic properties.
  • Another participant suggests starting with the definitions of ΔH, ΔS, and ΔG, indicating a focus on fundamental thermodynamic relationships.
  • A different participant inquires about the relationships of dh, ds, and dg in terms of dT and dP, seeking clarity on the differential forms of these properties.
  • One participant expresses uncertainty about how to derive ΔH and ΔS, questioning whether additional information is available at other temperatures.
  • Another participant speculates that the expression above the table may represent a recommended functional form for pressure, questioning if it constitutes an equation of state.

Areas of Agreement / Disagreement

Participants have not reached a consensus on how to proceed with the problem, and multiple viewpoints regarding the interpretation of the provided data and equations remain. Uncertainty exists about the sufficiency of the given information.

Contextual Notes

Participants have noted limitations regarding the available data, specifically the lack of equations of state and potential missing information at different temperatures, which may affect the analysis.

deltasmile
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Homework Statement


Hello, i am given an isothermal transition for nitrogen, N2, where temperature is constant at 700K, p1=1bar, and p2=100bar.
For this problem i am not allowed to use any equations of states, such as Benedict-Webb-Rubin, or Beattie-Bridgeman. Rather i am given only Cp data, which is in the table below. From only this data below for nitrogen i must determine the Enthalpy, Entropy, and Chemical Potential for the transition phase.
I am also given the equation below, which I am not too sure how to apply it to the problem.

Homework Equations


R*T (a + b v^-1 + c v^-2 + d v^-3)
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Start with definitions of the ΔH, ΔS and ΔG.
 
What are dh, ds, and dg in terms of dT and dP?
 
##\Delta G## is easy, but I still haven't figured out how to get ##\Delta H## and ##\Delta S##. Are you sure this is the only information they give you? Do they provide any information at any other temperature?
 
I'm guessing that the expression appearing above the table is the functional form they are recommending for the pressure. This is the equation of state. Am I correct?
 
Last edited:

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