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Answers to Readers' Questions on Chemistry:
Atomic Weight
The following 2 comments and questions have been sent in. They are listed according to date.
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What is the Avogadro number?
Question
February 19, 2008
I do not understand the formula An=6..02x10-23.
According to the explanation given in the lesson the gram weight of all atoms would be the same. However I know that that is not true. Do you multiply the molecule weight by the product of the An formula?
Thanks, Bill.
Billy - USA
15398
Answer
"An" stands for the Avogadro number, which is the number of atoms in 1 mole. In other words one mole of a substance has 6.02x10^23 atoms in it.
A gram-mole is the quantity of a substance whose mass in grams is equal to its formula weight. Thus a gram-mole of Carbon-12 would equal 12 grams.
It is a difficult concept to understand.
Convert atomic percentage to weight percentage
Question
August 2, 2007
How to convert atomic percentage into weight percentage and vice versa.?
dhana - India
14148
Answer
Atomic percent is the the number of atoms of a doping agent divided by the number of atoms of the solution. The number of atoms is determined from the moles of the substance, which in turn relates the its atomic number.
A mole (mol) is defined as the number of grams of a substance that is equal to its atomic or molecular weight.
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