Talk:Ideal solution

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no

[edit] Merge

I would like to propose merging this article and Ideal mixture. The two articles appear to cover very similar topics.--GregRM 16:55, 2 February 2007 (UTC)

[edit] sloppy math

"The vapor phase is an ideal gas so:

"

This equation is wrong because it is not dimensionally consistent. The chemical potential has dimensions of energy per particle, while RT ln of pressure has units of energy per particle times log of pressure. Obviously, the quantity in the logarithm is meant to be normalized by either the total pressure or some standard pressure, perhaps 1 bar. As written, the equation can't be correct. —Preceding unsigned comment added by ChrisChiasson (talk • contribs) 22:57, 8 September 2007 (UTC)

It is correct. The dimensions of chemical potential are energy per particle. The dimensions of R are energy per particle divided by temperature. When multiplied by the temperature the term RT yeilds energy per particle and is consistent with the dimensions of chemical potential. The log term is normalized as you said and has no units. A correction might be to explicitly show division by 1 bar for the normalization.

Just because people understand to use the equation differently that it is written does not make the equation correct. Also, the required normalization is dependent on the standard pressure which has been absorbed into the ideal chemical potential term. It is probably 1 bar in many cases, but it would be helpful if someone could come up with something authoritative and hopefully comprehensive. (a derivation of the ideal chemical potential term would be instructive, ala http://phasediagram.dk/chemical_potentials.htm )ChrisChiasson 07:26, 7 October 2007 (UTC)

The pressures should indeed be relative to standard pressure (1 bar) and omitting is sloppy. But the more fundamental problem is that the derivation is circular since Raoult's Law is best described as a *consequence* of the chemical potential of a ideal mixture. The chemical potential is itself best explained in terms of the entropy of mixing. 84.92.241.186 (talk) 12:12, 30 December 2007 (UTC)

[edit] Rework

Once I got started, it was hard to resist reworking the page. Hopefully the result flows better and fixes the problems above. 84.92.241.186 (talk) 13:31, 30 December 2007 (UTC)