Avogadro's number

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Related to Avogadro constant: atomic mass unit, gas constant, Pv=nrt

Avogadro's number

(ävōgä`drō) [for Amedeo AvogadroAvogadro, Amedeo, conte di Quaregna
, 1776–1856, Italian physicist, b. Turin. He became professor of physics at the Univ. of Turin in 1820. In 1811 he advanced the hypothesis, since known as Avogadro's law, that equal volumes of gases under identical conditions of pressure
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], number of particles contained in one molemole,
in chemistry, a quantity of particles of any type equal to Avogadro's number, or 6.02×1023 particles. One gram-molecular weight of any molecular substance contains exactly one mole of molecules.
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 of any substance; it is equal to 602,252,000,000,000,000,000,000, or in scientific notation, 6.02252×1023. For example, 12.011 grams of carbon (one mole of carbon) contains 6.02252×1023 carbon atoms, and 180.16 grams of glucose, C6H12O6, contains 6.02252×1023 molecules of glucose. Avogadro's number is determined by calculating the spacing of the atoms in a crystalline solid through X-ray methods and combining this data with the measured volume of one mole of the solid to obtain the number of molecules per molar volume.

Avogadro's number

[¦a·və¦gäd·drōz ‚nəm·bər]
(physics)
The number (6.02 × 1023) of molecules in a gram-molecular weight of a substance.
References in periodicals archive ?
[20] Deslattes RD, Henins A, Schoonover RM, Carroll CL, Bowman HA (1976) Avogadro Constant - Corrections to an Earlier Report.
After cleaning, repolishing and remeasuring silicon orbs used for previous measurements, a team of researchers reported a new value of the Avogadro constant in Metrologia in March.
* the Avogadro constant NA is exactly 6.022 141 ...
The scientists estimated the Avogadro constant at 6.02214084 times [10.sup.23], with an uncertainty of only 30 parts per billion, they write in a paper published online October 12 at arXiv.org.
The last three constants are determined by other means, but are included since they are used in some of the other determinations Constant Symbol Planck constant h Josephson constant (SI) [K.sub.J] = 2e/h Electron mass [m.sub.e] Proton mass [m.sub.p] Avogadro constant [N.sub.A] Elementary charge e Josephson constant [K.sub.J-90] von Klitzing constant [K.sub.K-90] l/(fine-structure constant) l/[alpha] Rydberg constant [R.sub.[infinity]] Electron's atomic mass [m.sub.e]/[m.sub.u] Unc.
The factor [N.sub.A]/1000 converts number concentration into a molar concentration, [N.sub.A] is the Avogadro constant, and 1000 is the number of [cm.sup.3] in a liter (we use [cm.sup.3] to conform to laboratory practice).
To remedy these problems, researchers want to define the kilogram as a function of the Avogadro constant, which measures the number of molecules (6.023 x [10.sup.23]) present in a gas occupying 22.41 liters at fixed temperature and pressure.
This measurement was a key input needed to obtain an improved value for the Avogadro constant, a fundamental constant of nature related to the amount of substance, and which may one day lead to a new natural standard of mass.