Heaps of moles? – Mediating macroscopic and microscopic measurement of chemical substances

Wolff, Johanna

doi:10.1016/j.shpsa.2018.06.002

Cited by 4 publications

(3 citation statements)

References 14 publications

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“…to define the size of a murmuration in terms of number of starlings 9 . The application of new 'unit' names for larger counts might be considered by many as a more user friendly method of expression than using prefixes, as would be done traditionally in the SI-such as 'kilostarling'-but does have the drawback of requiring extra definitions to be agreed and introducing more chance of confusion 10 .…”

Section: Realisation Of Unitsmentioning

confidence: 99%

“…Especially in chemistry it has become important to distinguish between amount of substance and quantities that are counted [6,7]. The recent re-definition of the mole-based on a fixed numerical value of the Avogadro constant-has brought this into sharper focus [8,9]. Furthermore, current debates around the status of angle and other ratio quantities within the International System of Units (SI) have renewed interest in the treatment of the unit one within the SI [10].…”

Section: Introductionmentioning

confidence: 99%

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A metrological approach to quantities that are counted and the unit one

Brown

2021

Metrologia

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There has long been debate over how to treat dimensionless quantities, or quantities with the unit one, within the International System of Units (SI). These arguments have been brought into sharper focus because of the increasing application of metrological principles in areas such as chemistry, biology and nanoscience where counting measurements are common. This has caused debates about how the SI should address counting quantities and the unit one (symbol 1). This article reviews the types of quantities with the unit one, how these quantities may be expressed together with their uncertainty and how this relates to counting. The qualities of counting quantities are explored in more detail and the range of possibilities for dealing with the unit one for counting are discussed. It is proposed that the SI should allow only the unit one for counting, but that downstream of the SI there may well be benefits from standardising the use of more descriptive, technical area specific ‘units’ for expressing the results of counting. As with all measurement it is essential that a full description, in words, of the counting quantity being expressed accompanies the measurement result.

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Section: Realisation Of Unitsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A metrological approach to quantities that are counted and the unit one

Brown

2021

Metrologia

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“…The distinction being the basis of the differences between real and natural numbers and the natural lower indivisible limit that exists for countable aggregates and (i.e. one entity) that does not exist for continuous quantities [9,10]. The mole is the only base unit with this property (although we might want to discuss whether the ampere is similar or not [11].)…”

Section: Relationship Between Quantity and Unit Is Chemistrymentioning

confidence: 99%

What is a mole?

Brown

Brewer

2020

Metrologia

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The mole was the final base unit to be included in the International System of Units. This article explores: our understanding of the mole and its characteristics; its relationship with the base quantity, amount of substance, of which it is the base unit; and when alternative ways of expressing measurement results would be preferable. Importantly, since the SI is a practical system, this article also develops an understanding of when the concept of the mole is useful and meaningful. An important outcome is that the mole must consider elementary entities located in close enough vicinity such that they could, in theory, react or interact with each other stoichiometrically. Further, it is observed that the majority of practical uses of the mole relate to describing the composition of mixtures where, unusually, the concept of a mole of dissimilar elementary entities is often advantageous. It is also noted that where ratio and fractions are used it is essential to display the measurement units being used in full to clarify what quantities are being expressed.

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