Talk:Henry's law/Draft: Difference between revisions

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imported>Paul Wormer
imported>Boris Tsirelson
Line 63: Line 63:
which is Milton's expression.  Chemical engineers are not always aware of the reference state, usually they simply assume ''p''<sub>0</sub> = ''kc''<sub>0</sub> and say: take  ''p''<sub>0</sub> = 1 in the appropriate pressure unit.
which is Milton's expression.  Chemical engineers are not always aware of the reference state, usually they simply assume ''p''<sub>0</sub> = ''kc''<sub>0</sub> and say: take  ''p''<sub>0</sub> = 1 in the appropriate pressure unit.
--[[User:Paul Wormer|Paul Wormer]] 09:21, 13 October 2012 (UTC)
--[[User:Paul Wormer|Paul Wormer]] 09:21, 13 October 2012 (UTC)
: Thank you Paul; now I see. The key is, "''p''<sub>0</sub> = 1 in the appropriate pressure unit". But probably it should be stated in the article. --[[User:Boris Tsirelson|Boris Tsirelson]] 09:40, 13 October 2012 (UTC)

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 Definition The relationship between the amount of gas dissolved in a liquid and the partial pressure of that gas above the liquid. [d] [e]
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Wikipedia has a similar article

I was a significant contributor to the Wikipedia article with the same name as this CZ article. I have reworded and rearranged some it it somewhat, added some references and conformed it to a CZ article. - Milton Beychok 00:35, 18 February 2008 (CST)

Approval of Version 1

Congratulations on approval of version 1. Please keep discussions concerning further developments below this section. D. Matt Innis 02:32, 7 November 2008 (UTC)


Approval of Version 1.1

The Draft has been re-approved to version 1.1. D. Matt Innis 23:15, 15 December 2008 (UTC)


Re-approval is again needed

I made some signicant changes in the "Temperature dependence of Henry's law constant" to correct the formatting of the equations and their parameter definitions in that section. It needs re-approval again. Milton Beychok 20:54, 15 September 2009 (UTC)

A mistake?

"" probably should be "". --Boris Tsirelson 21:32, 24 September 2012 (UTC)

Thanks for finding that typo. I have now fixed it. Milton Beychok 17:23, 25 September 2012 (UTC)
Nice. I also bother about dimensions: are these and dimensionless? --Boris Tsirelson 16:35, 26 September 2012 (UTC)
Boris, I am not sure that I understand your question about dimensions. Just below the equation, the parameters are listed and noted that they have many different sets of dimensions. Then Table 1 lists the dimensions very often used .... but there are many others to be found in the technical literature.
and and are definitely not dimensionless. Shalom and good yomtov (a day late).Milton Beychok 17:16, 26 September 2012 (UTC)
If is not dimensionless then is a sum of quantities of different dimensions. Does it make sense? --Boris Tsirelson 19:32, 26 September 2012 (UTC)
Boris, I am not a mathematician and you have just lost me completely. In this article, p is the symbol for pressure and it may be expressed in measurement units (i.e., dimensions) of pascals or atmospheres or torrs or bars or kg-force per square centimeter, and many others. That is what I meant when I said it was not dimensionless. And that makes perfect sense to me.
Also, in this article, c is used as the symbol for concentration and it may be expressed in measurement units of mols of dissolved gas per liter of solution, or mols of dissolved gas per mol of solution, or mols of dissolved gas per cubic meter of solution, or cubic centimeters of dissolved gas per cubic centimeter of solution, or many other methods of expressing concentrations. And that also makes perfect sense to me.
Furthermore, since p = kH · c, the dimensions of kH depend on the dimensions used for expressing p and c. In other words, the dimensions of kH will be the dimensions of p divided by the dimensions of c.
Beyond explaining what I meant by dimensionless what the word "dimensions" means to me in this article's context, I cannot help you any further. Perhaps, reading some of the references (especially, reference 7) might solve your concerns. Or perhaps you could consult one of the chemical engineering professors at the University of Tel-Aviv. Milton Beychok 21:31, 26 September 2012 (UTC)
Boris, I realize that the word "dimensions" to you probably means the basic physical dimensions such as mass, length, time, and temperature (M, L, T, and Θ). But there are many equations in chemistry and in engineering whose parameters are expressed in units of measurement rather than in those basic physical dimensions ... and I "think" in those terms of those measurement units. Therefore, my answer to your question was that the parameters in Henry's Law are not dimensionless. However, I do not know if they are or are not dimensionless in terms of the basic physical dimensions. In my opinion, it really doesn't matter for equations such as Henry's Law which have been in use for over 200 years now. Milton Beychok 02:03, 27 September 2012 (UTC)

[Unindent]

Boris is right in that it would be more elegant to write

where p0 and c0 are the respective quantities for the same reference state. However, if one makes the assumption (which is implicit in Milton's reasoning):

then taking the natural logarithm on both sides

Exponentiating

which is Milton's expression. Chemical engineers are not always aware of the reference state, usually they simply assume p0 = kc0 and say: take p0 = 1 in the appropriate pressure unit. --Paul Wormer 09:21, 13 October 2012 (UTC)

Thank you Paul; now I see. The key is, "p0 = 1 in the appropriate pressure unit". But probably it should be stated in the article. --Boris Tsirelson 09:40, 13 October 2012 (UTC)