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CalebBell / thermo

Thermodynamics and Phase Equilibrium component of Chemical Engineering Design Library (ChEDL)
MIT License
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STP properties assume 298.15 K (instead of 273.15 K) #95

Closed yoelcortes closed 2 years ago

yoelcortes commented 2 years ago

Hi Caleb,

I am not sure if this is an issue because it is consistent throughout thermo, but "STP" chemical properties are calculated at 298.15 K instead of 273.15 K (in the Chemical and ChemicalConstantsPackage objects). Is there a reason for this? I believe STP is 273.15 K and 101325 Pa in most textbooks.

Thanks!

dalito commented 2 years ago

The use of STP in thermo matches my experience in Chemistry. In general, it is a good idea to explicitly say what is used as reference or link to an official standard document like ISO 8778. Wikipedia has an nice page that shows how many different "standards" are in use.

CalebBell commented 2 years ago

Hi, The main reason is the enthalpy of formation data is conventionally reported at a temperature of 298.15 K. Here is one example source.

https://atct.anl.gov/Thermochemical%20Data/version%201.122r/index.php

I pretty much gave up on trying to reconcile the different between 1 bar and 1 atm as a standard state though.

yoelcortes commented 2 years ago

Thanks! Looking at all the different standards (kinda contrary to the name), this makes sense now.