Avogadro Constant
In chemistry and physics, the Avogadro constant (symbols: L, NA) is defined as the number of constituent particles (usually atoms or molecules) in a mole of the substance. It is a dimensionless number and has the value 6.02214129(27)×1023 mol−1. Changes in the SI units are proposed that will change the constant to exactly 6.02214X×1023 when it is expressed in the unit mol−1 (see New SI definitions).
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Some articles on avogadro constant:
... The number of atoms in a mole, a quantity known as the Avogadro constant, is experimentally determined, and the current best estimate of its value is 6.02214129 ... This new definition of the kilogram proposed to fix the Avogadro constant at precisely 6.02214X×10^23 with the kilogram being defined as “the mass equal to that of 1000⁄12 · 6.02214X ... By fixing the Avogadro constant, the practical effect of this proposal would be that the uncertainty in the mass of a 12C atom—and the magnitude of the kilogram—could be no better than the current 50 ppb ...
... If the Avogadro constant NA and the Faraday constant F are independently known, the value of the elementary charge can be deduced, using the formula (In other words, the charge of one mole of electrons ...
... Another Avogadro constant-based approach, known as the Avogadro project, would define and delineate the kilogram as a softball-size (93.6 mm diameter) sphere of silicon atoms ... Experiments are being performed on the Avogadro Project’s silicon spheres to determine whether their masses are most stable when stored in a vacuum, a ... All silicon-based approaches would fix the Avogadro constant but vary in the details of the definition of the kilogram ...
... The International Avogadro Coordination (IAC), often simply called the "Avogadro project", is a collaboration begun in the early 1990s between various national metrology institutes to ... of the efforts to redefine the kilogram in terms of a universal physical constant, rather than the International Prototype Kilogram, and complements the measurements of the ... International System of Units (SI), a measurement of the Avogadro constant is an indirect measurement of the Planck constant The measurements use highly polished spheres of ...
... The Avogadro constant NA is determined as the ratio of the mass of one mole of electrons to the mass of a single electron The mass of one mole of electrons is the "relative atomic mass ... The uncertainty in the value of the Planck constant limits the knowledge of the masses of atoms and subatomic particles when expressed in SI units ...
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