Talk:Concentration: Difference between revisions
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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, [[User:Milton Beychok|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)]]. --[[User:Daniel Mietchen|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 ''c<sub>B </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. | |||
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) | |||
Revision as of 00:53, 9 May 2009
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)
- ↑ NIST Guide to SI Units NIST website, accessed February 1, 2009. (Scroll down to item 18)
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