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2007-07-27 20:51:34 · 19 answers · asked by Anonymous in Science & Mathematics Chemistry

19 answers

The Avogadro constant (symbols: L, NA), also called the Avogadro number and, in German scientific literature, sometimes also known as the Loschmidt constant/number, is formally defined to be the number of "entities" in one molethat is the number of carbon-12 atoms in 12 grams (0.012 kg) of unbound carbon-12 in its ground state. The current best estimate of this number is .

N( A) = (6.02214179+0.00000030) x 10^23 mole^-1

& (6.02214179-0.00000030) x 10^23 mole^-1

2007-07-27 21:14:20 · answer #1 · answered by Anonymous · 1 0

Several answers mention that there are no units on Avogadro's Number. This is incorrect. The unit is mol-1, as is given in at least one answer.

Also, an answer indicated that Loschmidt's Number is another name (in Germany) for Avogadro's Number. The usage may have shifted, but I was taught that Loschmidt's Number was the number of molecules of gas per cubic centimeter.

2007-07-28 19:45:09 · answer #2 · answered by ChemTeam 7 · 0 0

Avogadro is the name of the scientist. He created an Equation, that is named after him and used extensively, in India you will find this Information in any Chemistry book for Intermediate science.

Other sources:

Chemistry professor, or physics professor.
Internet.
Library.
Book stores.

2007-07-28 04:00:43 · answer #3 · answered by minootoo 7 · 0 0

Avogadro's Value :
Avogadro's number, N A , is the fundamental physical constant that links the macroscopic physical world of objects that we can see and feel with the submicroscopic, invisible world of atoms. In theory, N A specifies the exact number of atoms in a palm-sized specimen of a physical element such as carbon or silicon.

The name honors the Italian mathematical physicist Amedeo Avogadro (1776-1856), who proposed that equal volumes of all gases at the same temperature and pressure contain the same number of molecules. Long after Avogadro's death, the concept of the mole was introduced, and it was experimentally observed that one mole (the molecular weight in grams) of any substance contains the same number of molecules. This number is Avogadro's number, although he knew nothing of moles or the eponymous number itself.

Today, Avogadro's number is formally defined to be the number of carbon-12 atoms in 12 grams of unbound carbon-12 in its rest-energy electronic state. The current state of the art estimates the value of N A , not based on experiments using carbon-12, but by using x-ray diffraction in crystal silicon lattices in the shape of a sphere or by a watt-balance method. According to the National Institute of Standards and Technology (NIST), the current accepted value for N A is:

N A = (6.0221415 ± 0.0000010) × 10^23

This definition of N A and the current experiments to estimate it, however, both rely on the precise definition of a gram. Originally the mass of one cubic centimeter of water at exactly 3.98 degrees Celsius and atmospheric pressure, for the past 117 years the definition of one gram has been one-thousandth of the mass of "Le Gran K," a single precious platinum-iridium cylinder stored in a vault in Sèvres, France. The problem is that the mass of Le Gran K is known to be unstable in time. Periodic cleanings and calibration measurements result in abrasion of platinum-iridium and accretion of cleaning chemicals.

These changes cannot be measured exactly, simply because there is no "perfect" reference against which to measure them—Le Gran K is always exactly one kilogram, by definition. It is estimated that Le Gran K may have changed about 50 micrograms—that is, roughly by about 150 quadrillion (1.5 × 1017) atoms—since it was constructed. This implies that by current measurement conventions, the mass of a single atom of carbon-12 is changing in time, whereas modern theory postulates that it remain constant.

2007-07-29 01:08:44 · answer #4 · answered by sb 7 · 0 1

6.022 x 10 to the power 23

2007-07-28 04:18:53 · answer #5 · answered by ► Anx Rox ◄ 3 · 0 0

Its 6.023*10^23
Its the value of 1mole of substance.

2007-07-28 16:02:27 · answer #6 · answered by Nikhil B 2 · 0 0

6.022 X 10^23 IS AVOGADRO NUMBER

2007-07-28 10:50:11 · answer #7 · answered by babaideep 1 · 0 0

6.023 into 10 to the power 23

2007-07-28 03:55:40 · answer #8 · answered by Gp06 2 · 0 1

6.022 x 10^23

2007-07-28 08:12:09 · answer #9 · answered by Coco55 3 · 0 0

6.022 x 10^23

2007-07-28 03:55:02 · answer #10 · answered by Anonymous · 0 0

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