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Name: Julie R.
Status: educator
Age: 40s
Location: N/A
Country: N/A
Date: 1/9/2005


Question:
How or Why is the term "mole" used as the unit for Avogadro's constant?


Replies:
Julie R.,

For a given molecule, one mole is a mass (in grams) whose number is equal to the atomic mass of the molecule. For example, the water molecule has an atomic mass of 18, therefore one mole of water weighs 18 grams. An atom of neon has an atomic mass of 20, therefore one mole of neon weighs 20 grams. In general, one mole of any substance contains Avogadro's Number ( 6.02 x 10^23) of molecules or atoms of that substance. This relationship was first discovered by Amedeo Avogadro (1776-1858) and he received credit for this after his death. I hope that this is helpful.

Sincerely,
Bob Trach


The question asks about the origin of the term "mole." The word "mole" has nothing to do with the animal that burrows under the ground.

Mole is the English version of the German word "Mol" which is short for Molekulargewicht, the "molecular weight."

Back about 200 years ago scientists were trying to figure out what substances were made of. They first worked on gases and gas molecules, and got that figured out pretty well. Then they worked on the atoms and molecules that make up solid substances. They needed a unit of measure that connected the mass of a molecule or atom with how many of them there were. They settled on Avogadro's number being useful.

The terms mole, gram formula weight, and gram molecular weight all mean the same thing.

Bob Erck



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