User talk:WilfriedC

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About your addition to the Vapor pressure article
Wilfried, in your equation for estimating the vapor pressure of a solid:


 * $$ln\,P^S_{solid} = ln\,P^S_{liquid} - \frac{\Delta H_m}{R} \left( \frac{1}{T} - \frac{1}{T_m} \right)$$

You need to more clearly define $$P^S_{liquid}$$ ... is it the liquid vapor pressure at the melting point? If so, that should be clearly stated.

Also, is there really any need for the superscript S? Is it not sufficient to simply use $$P_{solid}$$ and $$P_{liquid}$$ ... rather than $$P^S_{solid}$$ and $$P^S_{liquid}$$ ? mbeychok (talk) 04:11, 8 December 2008 (UTC)


 * Milton, $$P^S_{liquid}$$ is the extrapolated vapor pressure of the supercooled liquid at the temperature T and is normally calculated by extrapolating the vapor pressure of the liquid to temperatures below the melting point by vapor pressure equations. So, this is not the vapor pressure at Tm. I'll try to make this clearer.
 * The superscript S indicates that this pressure is a pressure at the vapor-liquid or vapor-solid coexistence curve and stands for saturation. This might not be necessary because it is clear in the context but it is correct. --WilfriedC (talk) 11:49, 8 December 2008 (UTC)


 * Wilfried, thanks for your response and for agreeing that $$P^S_{liquid}$$ needs more definition. As for the superscript S, I did not not mean to intimate that it was incorrect. I only meant that, if it was not necessary, why not delete it? I, for one, was somewhat confused by it. Regards, mbeychok (talk) 18:38, 8 December 2008 (UTC)


 * Milton, I have now added some hopefully sufficient clarifications but kept the 'S'. This index is commonly used and makes the kind of pressure the article is about clearer and separates this from non-equilibrium pressures as described by equation of states. So, I'd like to keep it but I won't object if somebody removes it. --WilfriedC (talk) 19:05, 8 December 2008 (UTC)


 * Wilfried, the image Image:Vapor Pressure Curve of Liquid and Solid Benzene.png appears to have been uploaded by you and Eigenes Werk is listed as the source. Would you please tell me who actually drew the image ... was it you or Eigenes Werk? Thanks in advance. mbeychok (talk) 03:13, 9 December 2008 (UTC)


 * Yes, I made this diagram. "Eigenes Werk" is simply German for "Own Work". I made the basic diagram with Dortmund Data Bank related software which i can use for creating such diagrams and added some descriptions with Paint.net. --WilfriedC (talk) 12:19, 9 December 2008 (UTC)


 * Thanks very much, Wilfried. mbeychok (talk) 21:45, 9 December 2008 (UTC)

Azeotrope prediction
Are there some methodes, perhaps based on group contribution, to predict azeotropes formation beetween various chemicals?--MagnInd (talk) 23:37, 5 December 2011 (UTC)

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