Difference between revisions of "Amount of substance"
Physchim62 (talk | contribs) (→Definition) |
Physchim62 (talk | contribs) (→Definition) |
||
| Line 2: | Line 2: | ||
==Definition== | ==Definition== | ||
| − | Unlike the other base quantities in the ISQ, amount of substance is not defined by [[ISO 31]]:1992.<ref name="MiltonMills">{{citation | title = Amount of substance and the proposed redefinition of the mole | first1 = M. J. T. | last1 = Milton | first2 = I. M. | last2 = Mills | journal = Metrologia | year = 2009 | volume = 46 | pages = 332–38 | doi = 10.1088/0026-1394/46/3/022}}.</ref> The International Union for Pure and Applied Chemistry (IUPAC) has used the following definition<ref>{{ | + | Unlike the other base quantities in the ISQ, amount of substance is not defined by [[ISO 31]]:1992.<ref name="MiltonMills">{{citation | title = Amount of substance and the proposed redefinition of the mole | first1 = M. J. T. | last1 = Milton | first2 = I. M. | last2 = Mills | journal = Metrologia | year = 2009 | volume = 46 | pages = 332–38 | doi = 10.1088/0026-1394/46/3/022}}.</ref> The International Union for Pure and Applied Chemistry (IUPAC) has used the following definition<ref>{{GreenBookOld1st}}.</ref><ref>{{GreenBook3rd|page=53}}.</ref><ref name="CCQM15">{{citation | title = Consultative Committee for Amount of Substance: metrology in chemistry (CCQM): Report of the 15th meeting (22–24 April 2009) | url = http://www.bipm.org/utils/common/pdf/CCQM15.pdf | publisher = International Bureau for Weights and Measures | location = Sèvres, France | page = 7}}.</ref> (or varients<ref>{{GreenBook2nd|page=46}}.</ref><ref>{{GoldBookRef|title=amount of substance, ''n''|file=A00297|accessdate=2010-03-29}}.</ref>): |
<blockquote> | <blockquote> | ||
Amount of substance is a quantity proportional to the number of specified elementary entities ''N'' in a sample. The proportionality constant is the same for all substances, and is the reciprocal of the Avogadro constant ''N''<sub>A</sub>, so that amount of substance is defined by the equation ''n'' = ''N''/''N''<sub>A</sub>.<br/>The entities may be atoms, molecules, ions, electrons, other particles, or specified groups of particles. | Amount of substance is a quantity proportional to the number of specified elementary entities ''N'' in a sample. The proportionality constant is the same for all substances, and is the reciprocal of the Avogadro constant ''N''<sub>A</sub>, so that amount of substance is defined by the equation ''n'' = ''N''/''N''<sub>A</sub>.<br/>The entities may be atoms, molecules, ions, electrons, other particles, or specified groups of particles. | ||
Revision as of 19:24, 29 March 2010
Amount of substance (symbol: n) is a physical quantity, and one of the seven base quantities in the International System of Quantities.
Definition
Unlike the other base quantities in the ISQ, amount of substance is not defined by ISO 31:1992.[1] The International Union for Pure and Applied Chemistry (IUPAC) has used the following definition[2][3][4] (or varients[5][6]):
Amount of substance is a quantity proportional to the number of specified elementary entities N in a sample. The proportionality constant is the same for all substances, and is the reciprocal of the Avogadro constant NA, so that amount of substance is defined by the equation n = N/NA.
The entities may be atoms, molecules, ions, electrons, other particles, or specified groups of particles.
The following definition has been proposed:[1][4]
Amount of substance is a quantity that measures the size of an ensemble of entities. It is proportional to the number of specified entities and the constant of proportionality is the same for all substances. The entities may be atoms, molecules, ions, electrons, other particles, or specified groups of particles.
References
- ↑ 1.0 1.1 Milton, M. J. T.; Mills, I. M. Amount of substance and the proposed redefinition of the mole. Metrologia 2009, 46, 332–38. DOI: 10.1088/0026-1394/46/3/022.
- ↑ McGlashan, M. L. Manual of symbols and terminology for physicochemical quantities and units. Pure Appl. Chem. 1970, 21 (1), 1–44. DOI: 10.1351/pac197021010001; Physico-Chemical Quantities and Units; Royal Institute of Chemistry: London, 1971.
- ↑ Quantities, Units and Symbols in Physical Chemistry, 3rd ed.; Royal Society of Chemistry: Cambridge; p 53. ISBN 0-85404-433-7.
- ↑ 4.0 4.1 Consultative Committee for Amount of Substance: metrology in chemistry (CCQM): Report of the 15th meeting (22–24 April 2009); International Bureau for Weights and Measures: Sèvres, France; p 7, <http://www.bipm.org/utils/common/pdf/CCQM15.pdf>.
- ↑ Quantities, Units and Symbols in Physical Chemistry, 2nd ed.; Blackwell Science: Oxford, 1993; p 46. ISBN 0-63203-5838, <http://old.iupac.org/publications/books/gbook/green_book_2ed.pdf>.
- ↑ amount of substance, n, <http://goldbook.iupac.org/A00297.html> (accessed 29 March 2010), Compendium of Chemical Terminology Internet edition; International Union of Pure and Applied Chemistry (IUPAC).
| Error creating thumbnail: Unable to save thumbnail to destination |
This page is currently licensed under the Creative Commons Attribution 3.0 Unported license and any later versions of that license. |
