Talk:Concentration: Difference between revisions

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imported>Milton Beychok
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==Wikipedia has an article with the same name==
== Many other expressions of concentration ==


I was a minor contributor to the WP article. I have completely re-written, re-formatted and expanded the WP article before uploading it here into CZ. [[User:Milton Beychok|Milton Beychok]] 01:45, 4 February 2009 (UTC)
Daniel, as you know, there are quite a few ways to express concentration other than moles per litre. For example:  


== I think you're wrong about "general common usage" ==
*mass per volume (mg/m³, kg/m³, pounds per gallon or lb/gal)
*parts per million by volume (ppmv) and parts per million by weight (ppmw)
*molality of solutions, which is moles per mass (mole/kg)
*mole fraction (moles of component x per total moles)
*percent by volume (%v) and percent by weight (%w)
Would it not be helpful to mention at least a few of the other ways of expressing concentration? Regards, [[User:Milton Beychok|Milton Beychok]] 20:06, 29 January 2009 (UTC)


When you write in the lede: "in general common usage, concentration is" so-and-so, I won't dispute that a '''fairly''' common usage is something like "the concentration of orange juice concentrate to water is one to three" or whatever.
:I stick to SI units as far as possible but sure, go ahead. I do not have particular plans for this one, just needed it for [[Concentration (disambiguation)]]. --[[User:Daniel Mietchen|Daniel Mietchen]] 03:38, 1 February 2009 (UTC)


A '''more''' common usage, I would submit, is "Pancho Gonzales displayed other-worldly powers of concentration as he came back from two sets down to...."
== This one sentence article should be merged into [[Concentration]]  ==


"Concentration" (and "focus") are such cliches these days that one can hardly listen to a sporting event without being battered by them on a once-a-minute basis, or so it seems to me. [[User:Hayford Peirce|Hayford Peirce]] 01:54, 4 February 2009 (UTC)
There is really no reason now to have this one-sentence [[Concentration (chemistry)]] article, when that one sentence is actually covered in the much larger and extensive [[Concentration]] article.


:Would you like me to change the wording to read "... and in fairly common usage ..."? Please let me know and I will do so. Its no big deal. However, I must say that what is "general common usage" depends on one's interests. Yes, "concentration" and "focus" are used quite a bit in sports reporting and commentating ... and "concentration" as used in science, engineering, technolgy and many industries is also used quite a bit (perhaps, even more so). So, I guess it depends on what turns you on.
The one sentence in this article is:
:'''In chemistry, concentration indicates what amount of a substance (measured in units of mole) is present in a given volume of reference (usually measured in units of litres or cubic metres).'''


:Again, just let me know and I will change the wording. I would like to know what you think of the [[Concentration]] article as a whole. I am finding, as a I use Google to search Citizendium that a great many of our existing articles have links to [[Concentration]] as used in science, engineering and etc. And I am only partially through my Google search. [[User:Milton Beychok|Milton Beychok]] 02:43, 4 February 2009 (UTC)
The Molarity section, one of the many sections in the [[Concentration]] article, states:
:'''''Molarity'' or ''molar concentration'' (in units of mol/L) denotes the number of moles of a given solute per litre of solution. The units of mol/L are commonly replaced by the symbol M.'''


::"fairly" would be fine; there might also be some way of tweaking it to something like "and in one fairly common usage." I'll take another look at it tomorrow -- inspiration may come overnight.... As for the article as a whole, I am overwhelmed by all the expertise in it and all the info. Wow!  Are you going to expand each of the headings, or is it pretty much in finished form? [[User:Hayford Peirce|Hayford Peirce]] 03:14, 4 February 2009 (UTC)
:'''The National Institute of Standards and Technology (NIST) of the United States considers the term molarity and the symbol M to be obsolete and recommends using the term ''amount-of-substance concentration of B'' (or ''concentration of B'') and the symbol ''c<sub>B&nbsp;</sub>'' with SI units of mol/m<sup>3</sup> or other SI acceptable units.<ref name=NIST>[http://physics.nist.gov/Pubs/SP811/sec11.html NIST Guide to SI Units]  NIST website, accessed February 1, 2009. (Scroll down to item 18)</ref>. This recommendation has not been universally implemented in academia or chemistry research yet.'''
Note that Molarity in the [[Concentration (chemistry)]] is expressed in the same ''mol/liter'' as is defined in this one sentence [[Concentration (chemistry)]] article.


:::I'll change the opening sentence to "fairly" for now and await your possible further inspiration. Do I plan to expand each of the headings? Not at the moment. The article now has everything I know on the subject. I will create the "Related Articles" and "Bibliography" subpages as soon as I can. As for upgrading the status from 2 to 1, I will wait 2-3 weeks to see if anyone comes up with any needed revisions or additions.
If there is no objection forthcoming in the next few days, I will merge this article into [[Concentration]] and I will add a new section on '''Mol per volume''' so that the merged article will then cover that concentration expression  as well. [[User:Milton Beychok|Milton Beychok]] 05:53, 9 May 2009 (UTC)
 
:::The monthly Write-a-Thon is tommorrow. Do you think you could get Aleta to credit this article as part of tomorrow's Write-a-thon even though I uploaded a6-7 hours ahead of time? (:>) Regards, [[User:Milton Beychok|Milton Beychok]] 03:42, 4 February 2009 (UTC)
 
::::I would think so -- the rules seem to be fairly informal, or at least a little bit stetchable from time to time.... [[User:Hayford Peirce|Hayford Peirce]] 03:53, 4 February 2009 (UTC)
 
::::[[CZ:Monthly_Write-a-Thon#Keen-as-mustard_and_jumped_the_gun|You're in]]! [[User:Chris Day|Chris Day]] 04:23, 4 February 2009 (UTC)

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 Definition:  In science, engineering and in general common usage: the measure of how much of a given substance there is in a given mixture of substances. [d] [e]
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Many other expressions of concentration

Daniel, as you know, there are quite a few ways to express concentration other than moles per litre. For example:

  • mass per volume (mg/m³, kg/m³, pounds per gallon or lb/gal)
  • parts per million by volume (ppmv) and parts per million by weight (ppmw)
  • molality of solutions, which is moles per mass (mole/kg)
  • mole fraction (moles of component x per total moles)
  • percent by volume (%v) and percent by weight (%w)

Would it not be helpful to mention at least a few of the other ways of expressing concentration? Regards, Milton Beychok 20:06, 29 January 2009 (UTC)

I stick to SI units as far as possible but sure, go ahead. I do not have particular plans for this one, just needed it for Concentration (disambiguation). --Daniel Mietchen 03:38, 1 February 2009 (UTC)

This one sentence article should be merged into Concentration

There is really no reason now to have this one-sentence Concentration (chemistry) article, when that one sentence is actually covered in the much larger and extensive Concentration article.

The one sentence in this article is:

In chemistry, concentration indicates what amount of a substance (measured in units of mole) is present in a given volume of reference (usually measured in units of litres or cubic metres).

The Molarity section, one of the many sections in the Concentration article, states:

Molarity or molar concentration (in units of mol/L) denotes the number of moles of a given solute per litre of solution. The units of mol/L are commonly replaced by the symbol M.
The National Institute of Standards and Technology (NIST) of the United States considers the term molarity and the symbol M to be obsolete and recommends using the term amount-of-substance concentration of B (or concentration of B) and the symbol cB  with SI units of mol/m3 or other SI acceptable units.[1]. This recommendation has not been universally implemented in academia or chemistry research yet.

Note that Molarity in the Concentration (chemistry) is expressed in the same mol/liter as is defined in this one sentence Concentration (chemistry) article.

If there is no objection forthcoming in the next few days, I will merge this article into Concentration and I will add a new section on Mol per volume so that the merged article will then cover that concentration expression as well. Milton Beychok 05:53, 9 May 2009 (UTC)

  1. ↑ NIST Guide to SI Units NIST website, accessed February 1, 2009. (Scroll down to item 18)
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