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How Much is a Mole?

Date: 11/17/2000 at 10:08:42
From: Lindsey
Subject: How much is a mole of something

I am working on a dimensional analysis problem for chemistry and the 
question requires you to know how many grams are in a mole. How many 
are there?

Date: 11/17/2000 at 10:14:50
From: Doctor Mitteldorf
Subject: Re: How much is a mole of something

A mole isn't a specific number of grams - it's a specific number of 
molecules. One mole of any material is 6.02*10^23 molecules of that 

The reason for this strange, rather large number is that it turns out 
to be a convenient way to work with macroscopic proportions. 

6.02*10^23 is called Avogadro's number, and it is the number of 
protons in a gram. That also makes it a conversion factor between 
atomic weight units and grams.
For example, a mole of hydrogen atoms weighs exactly 1 gram, because 
atomic hydrogen has atomic weight of 1. A mole of water is 18 grams of 
water, because each water molecule consists of 2 hydrogen atoms 
(atomic weight 1 each) + 1 oxygen atom (atomic weight 16 each).

- Doctor Mitteldorf, The Math Forum   
Associated Topics:
High School Physics/Chemistry

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