Abstract
The mole is a difficult concept. Surveys have shown that even many teachers do not have a proper understanding of it. To help to meet this problem, the SI/IUPAC formulation of the mole is carefully presented and explained. New SI proposals are also briefly discussed.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Notes
From Greek stoicheion, element. Often spelt “stoichiometric”.
IUPAC denote the relative mass of an atom by A r and of a molecule by M r.
This is most easily seen by considering a simple example, e.g. 2H2 + O2 → 2H2O. In this reaction, the number of H2 molecules reacting is equal to twice the number of O2 molecules reacting, as given by Eq. 4.
IUPAC denote the mass of an atom by m a and of a molecule or formula unit by m f.
At the 2011 meeting of the IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW), the Commission proposed that “amount of substance” be renamed “number of entities” and the mole be defined as a number. This confounds the two schemes.
References
Atkins, P.W., de Paula, J.: Physical Chemistry, 7th edn. Oxford University Press, Oxford (2002)
Becker, P., Bettin, H.: The Avogadro constant: determining the number of atoms in a single-crystal 28Si sphere. Phil. Trans. R. Soc. A 369, 3925–3935 (2011)
Censullo, A.C., Hill, T.P., Miller, J.: From the current “kilogram problem” to a proposed definition. Chem. Int. 33(5), 9–12 (2011)
Cohen, E.R., et al.: Quantities, Units and Symbols in Physical Chemistry, 3rd edn. IUPAC, RSC, Cambridge (2007)
DeToma, R.P.: Symbolic algebra and stoichiometry. J. Chem. Educ. 71, 568–570 (1994)
Furió, C., Azcona, R., Guisasola, J.: The learning and teaching of the concepts “amount of substance” and “mole”: a review of the literature. Chem. Educ. Res. Pract. 3, 277–292 (2002). www.uoi.gr/cerp
Gorin, G.: “Chemical amount” or “chemiance”: proposed names for the quantity measured in mole units. J. Chem. Educ. 59, 508 (1982)
Hill, T.P.: Criticisms of the proposed “new SI”. Accred. Qual. Assur. 16, 471–472 (2011)
Jeannin, Y.: A fixed Avogadro constant or a fixed carbon-12 molar mass: which one to choose? Chem. Int. 32(1), 8–11 (2010)
Knight, D.M.: Atoms and Elements. Hutchinson, London (1967)
Leonard, B.P.: Comments on recent proposals for redefining the mole and kilogram. Metrologia 47, L5–L8 (2010)
McGlashan, M.L.: Physico-chemical Quantities and Units. The Royal Institute of Chemistry, London (1968)
McGlashan, M.L.: The mole. Educ. Chem. 14, 189 (1977)
Miller, J., Hill, T.P., Censullo, A.: Unresolved concerns about the “new SI”. Accred. Qual. Assur. 16, 657–658 (2011)
Mills, I.M., Mohr, P.J., Quinn, T.J., Taylor, B.N., Williams, E.R.: Adapting the International System of Units to the twenty-first century. Phil. Trans. R. Soc. A 369, 3907–3924 (2011)
Mills, I.M., Milton, M.: Amount of substance and the mole. Chem. Int. 31(2), 3–7 (2009)
Milton, M.J.T.: A new definition of the mole based on the Avogadro constant: a journey from physics to chemistry. Phil. Trans. R. Soc. A 369, 3993–4003 (2011)
Milton, M.J.T., Mills, I.M.: Amount of substance and the proposed redefinition of the mole. Metrologia 46, 332–338 (2009)
Nelson, P.G.: The elusive mole. Educ. Chem. 28, 103–104 (1991)
Nelson, P.G.: Teaching chemistry progressively: from substances, to atoms and molecules, to electrons and nuclei. Chem. Educ. Res. Pract. 3, 215–228 (2002). www.uoi.gr/cerp
Nelson, P.G.: The new SI. Chem. World, October p 43; December p 42 (2011)
Ostwald, W.: Hand-und Hilfsbuch zur Ausführung Physiko-Chemischer Messungen. Engelmann, Leipzig (1893)
Packer, J.E.: Difficulties with stoichiometry. Educ. Chem. 25, 92–95 (1988)
Pavese, F.: Some reflections on the proposed redefinition of the unit for the amount of substance and of other SI units. Accred. Qual. Assur. 16, 161–165 (2011)
Price, G.: A skeptic’s review of the new SI. Accred. Qual. Assur. 16, 121–132 (2011)
Taylor, B.N.: Molar mass and related quantities in the new SI. Metrologia 46, L16–L19 (2009)
Wheatley, N.: On the dimensionality of the Avogadro constant and the definition of the mole. Metrologia 48, 71–82 (2011)
Yang, L., Mester, Z., Sturgeon, R.E., Meija, J.: Determination of the atomic weight of 28Si-enriched silicon for a revised estimate of the Avogadro constant. Anal. Chem. 84, 2321–2327 (2012)
Acknowledgments
I am grateful to Dr. Chris Botton for encouraging me to write this paper and to Professor Brian P. Leonard for drawing my attention to the new SI proposals.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Nelson, P.G. What is the mole?. Found Chem 15, 3–11 (2013). https://doi.org/10.1007/s10698-013-9185-1
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10698-013-9185-1