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Latent Heat Of Vaporation

latent heat

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#1 rikakose

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Posted 07 May 2018 - 09:26 AM

There is an equation for estimating the boiling point of pure component at different pressure.

 

ln(P1/P2)=-Hevap/R X (1/T1-1/T2)

 

Since the enthalpy of vaporation is changing with pressure/temperature (boiling point), is the equation reliable?

 

 



#2 MrShorty

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Posted 07 May 2018 - 10:30 AM

I think a lot depends on what you mean by "reliable"?

 

A quick check based on water (using NIST's REFPROP for the reference calculations), it appears that your simplified equation (appears to be based on the Clausius-Clapeyron equation) is off by about 1 C at 0.25 atm and about 0.25 C at 3 atm. Is that "reliable"? For organics (tested on methanol, toluene, octane), the errors are larger (2-3 C at 0.25 atm and 1.5 to 2.5 C at 3 atm). I suggest that you perform similar calculations for test compounds that make sense to you, then determine exactly what "reliable" means in terms of those errors.



#3 breizh

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Posted 08 May 2018 - 05:10 AM

https://www.ncbi.nlm...les/PMC4294737/

 

Take a look.

Breizh

 






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