Mole, the SI Unit of Amount of Substance, and Its Re-Definition by Fixing the Numerical Value of the Avogadro Constant

2018 ◽  
Vol 35 (4) ◽  
pp. 405-412
Author(s):  
Kyoung-Seok Lee
Keyword(s):  
Amount Of Substance ◽  
Avogadro Constant

scholarly journals A critical review of the proposed definitions of fundamental chemical quantities and their impact on chemical communities (IUPAC Technical Report)

2017 ◽  
Vol 89 (7) ◽  
pp. 951-981 ◽  
Author(s):  
Roberto Marquardt ◽  
Juris Meija ◽  
Zoltan Mester ◽  
Marcy Towns ◽  
Ron Weir ◽  
...  
Keyword(s):  
Critical Review ◽  
Planck Constant ◽  
Amount Of Substance ◽  
Work Related ◽  
Avogadro Constant ◽  
Technical Report ◽  
Measurements In Chemistry ◽  
Definition Of ◽  
New Si

AbstractIn the proposed new SI, the kilogram will be redefined in terms of the Planck constant and the mole will be redefined in terms of the Avogadro constant. These redefinitions will have some consequences for measurements in chemistry. The goal of the Mole Project (IUPAC Project Number 2013-048-1-100) was to compile published work related to the definition of the quantity ‘amount of substance’, its unit the ‘mole’, and the consequence of these definitions on the unit of the quantity mass, the kilogram. The published work has been reviewed critically with the aim of assembling all possible aspects in order to enable IUPAC to judge the adequateness of the existing definitions or new proposals. Compilation and critical review relies on the broadest spectrum of interested IUPAC members.

The importance of the Avogadro constant for amount-of-substance measurements

1998 ◽  
Vol 361 (3) ◽  
pp. 227-234 ◽  
Author(s):  
P. De Bièvre ◽  
S. Valkiers ◽  
P. D. P. Taylor
Keyword(s):  
Amount Of Substance ◽  
Avogadro Constant

scholarly journals A new definition for the mole based on the Avogadro constant: a journey from physics to chemistry

2011 ◽  
Vol 369 (1953) ◽  
pp. 3993-4003 ◽  
Author(s):  
Martin J. T. Milton
Keyword(s):  
Measurement Uncertainty ◽  
Early Development ◽  
International System ◽  
Atomic Masses ◽  
Amount Of Substance ◽  
Avogadro Constant ◽  
System Of Units ◽  
Considerable Debate ◽  
Recent Addition ◽  
Base Units

The mole is the most recent addition to the set of base units that form the International System of Units, although its pre-cursor the ‘gram-molecule’, had been in use by both physicists and chemists for more than 120 years. A proposal has been published recently to establish a new definition for the mole based on a fixed value for the Avogadro constant. This would introduce consistent relative uncertainties for the molar and the atomic masses while making no change to the system of relative atomic masses (‘atomic weights’). Although the proposal would have little impact on the measurement uncertainty of practical work, it has stimulated considerable debate about the mole and the nature of the quantity amount of substance. In this paper, the rationale for the new definition is explained against the background of changes in the way the quantity amount of substance has been used, from its first use during the early development of thermodynamics through to the use of the ‘number of gram-molecules’ at the end of the nineteenth century.

scholarly journals The Avogadro constant: determining the number of atoms in a single-crystal 28 Si sphere

2011 ◽  
Vol 369 (1953) ◽  
pp. 3925-3935 ◽  
Author(s):  
Peter Becker ◽  
Horst Bettin
Keyword(s):  
Single Crystal ◽  
Accurate Determination ◽  
Silicon Crystal ◽  
Fundamental Constant ◽  
Planck Constant ◽  
Amount Of Substance ◽  
Avogadro Constant ◽  
Unique Approach ◽  
Definition Of ◽  
Si Isotope

The Avogadro constant, the number of entities in an amount of substance of one mole, links the atomic and the macroscopic properties of matter. Since the molar Planck constant—the product of the Planck constant and the Avogadro constant—is very well known via the measurement of the Rydberg constant, the Avogadro constant is also closely related to the Planck constant. In addition, its accurate determination is of paramount importance for a new definition of the kilogram in terms of a fundamental constant. Here, we describe a new and unique approach to determine the Avogadro constant from the number of atoms in 1 kg single-crystal spheres that are highly enriched with the 28 Si isotope. This approach has enabled us to apply isotope dilution mass spectroscopy to determine the molar mass of the silicon crystal with unprecedented accuracy. The value obtained, N A =6.022 140 82(18)×10 23  mol −1 , is now the most accurate input datum for a new definition of the kilogram.

In Vivo Wound Healing Activity of Spirulina platensis

2019 ◽  
Vol 18 (1) ◽  
pp. 06-16
Author(s):  
R. Seghiri ◽  
A. Essamri
Keyword(s):  
Wound Healing ◽  
Spirulina Platensis ◽  
Therapeutic Agent ◽  
Conventional Medicine ◽  
Folk Medicine ◽  
Chemical Burns ◽  
Amount Of Substance ◽  
Test Population ◽  
Wound Healing Activity

Spirulina is a microalga used in traditional folk medicine in Morocco for the treatment of various health disorders. The wound healing activity of Moroccan Spirulina is unknown. In the current study, aqueous extracts of Spirulina platensis were investigated for acute toxicity and wound healing activity in Swiss Albino mice and White New Zealand rabbits, respectively. The LD50 (amount of substance required to kill 50% of the test population) of the microalga was greater than 5,000 mg/kg. Healing after application of the same amount of ointment on differently induced (mechanical, chemical, and thermal) wounds was about the same, over five weeks. Aqueous extract had remarkable healing activity on rabbits’ skin, possessing significantly greater healing effect for mechanical and chemical burns than controls. Moreover, the hair growing time was faster in treated groups; Spirulina-treated groups did not show any contamination with microbes compared to others. This study affirms that Spirulina platensis can be considered as a potential therapeutic agent for wound healing not only as a complementary medicine but also in conventional medicine.

The Avogadro constant — Recent results on the molar volume of silicon

1987 ◽  
Vol IM-36 (2) ◽  
pp. 161-165 ◽  
Author(s):  
Peter Seyfried ◽  
Reiner Balhorn ◽  
Manfred Kochsiek ◽  
Andrzej F. Kozdon ◽  
H.-J. Rademacher ◽  
...  
Keyword(s):  
Molar Volume ◽  
Avogadro Constant

Amount of substance: an alternative proposal

1978 ◽  
Vol 13 (5) ◽  
pp. 269-272 ◽  
Author(s):  
Richard G Forbes
Keyword(s):  
Amount Of Substance ◽  
Alternative Proposal

Highly sensitive refractive index sensor for detection of Hg2+ based on Fano-like resonance in metal-dielectric-metal meta-structure

2021 ◽  
Author(s):  
Shuangxiu Yuan ◽  
Xuebo Sun ◽  
Jing Li ◽  
Yan Li ◽  
Fufang Su ◽  
...  
Keyword(s):  
Refractive Index ◽  
Limit Of Detection ◽  
Wavelength Shift ◽  
Refractive Index Sensor ◽  
Large Area ◽  
Amount Of Substance ◽  
Resonance Modes ◽  
Dipole Resonance ◽  
Highly Sensitive ◽  
Fabry Perot

Abstract We experimentally and theoretically investigate Fano-like resonance in large-area Au/SiO2/Au nano-patches meta-structure, which is originating from the coupling between Fabry Perot resonance and magnetic dipole resonance modes. A highly sensitive refractive index sensor based on the lineshape analysis is obtained. The extracted wavelength shift with the amount of substance of Hg2+ changing from 10-3 pmol to 1 nmol has a linear dependence, and the sensitivity can reach to ultra-low limit of detection (LOD) as 10-3 pmol. This study may provide an approach for the development and modification in sensing.

Sign in / Sign up

Export Citation Format

Share Document