Calculating Gibbs Free Energy w/o Standard Entropy

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Discussion Overview

The discussion revolves around the challenge of calculating Gibbs free energy for specific chemical reactions in a Chemical Engineering context, particularly when standard entropy values for certain compounds, such as 1-Buten-3-yne and Styrene, are not readily available. The focus is on finding alternative methods or resources to obtain the necessary thermodynamic data.

Discussion Character

  • Homework-related
  • Technical explanation

Main Points Raised

  • One participant expresses difficulty in calculating Gibbs free energy due to the unavailability of standard entropy values for specific compounds.
  • Another participant suggests searching for "physical and chemical data" related to the compounds in question.
  • A participant questions whether standard entropy can be calculated using specific heat, heat capacity, or enthalpy data.
  • One reply advises focusing on free energies of formation instead of entropies, recommending specific resources such as Perry's Chemical Engineers' Handbook and TRC Thermodynamic Tables.
  • A later reply indicates success in finding the necessary data for 1-Buten-3-yne through the suggested resources.

Areas of Agreement / Disagreement

Participants generally agree on the need for alternative resources to find thermodynamic data, but there is no consensus on the best approach to calculate standard entropy or Gibbs free energy without it.

Contextual Notes

Participants mention specific resources and methods for obtaining thermodynamic data, but there are unresolved questions regarding the calculation of standard entropy from other thermodynamic properties.

bg93
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This is for my Chemical Engineering class, but it comes down to a thermodynamics question. I need to calculate the gibbs free energy for a few reactions, problem is some of the compounds (1-Buten-3-yne and Styrene) do not have standard entropy values that I can find. Without a standard entropy I cannot calculate the gibbs free energy as a function of temperature. I know they have to be out thre somewhere but I cannot find after extensive googling. Can anyone point me in the right direction?
 
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Try looking for "physical and chemical data" for the families of interest.

I quickly found this one: http://www2.ucdsb.on.ca/tiss/stretton/database/organic_thermo.htm
 
Sweet, that got me Styrene (I was actually previously there when I was looking for 1-Buten-3-yne).

Is there no way to calculate standard entropy knowing the specific heat/heat capacity or enthalpy?

I still can't find 1-Buten-3-yne. All the links are purple!
 
You should really be looking directly for the free energies of formation rather than the entropies of formation. There is a table of free energies of formation in Perry's Chemical Engineers' Handbook. Another possible source is TRC Thermodynamic Tables, Hydrocarbons, Thermodynamics Research Center, Texas A & M, also, Journal of Physical and Chemical Reference Data, 11, supp.2, 1982.
 
Found it through that, thank you very much, that's exactly what I was looking for!
 

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