The mole concept and associated calculations. **More good stuff available at: www.wsautter.com and http://www.youtube.com/results?search_query=wnsautter&aq=f

1. Moles  Atoms
Moles  Grams
MOLES
Copyright Sautter 2014

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What is a mole?
•A mole is a name for a number just like the
word dozen is a name for a number.
•As you know, a dozen means the number 12.
•A mole is a number too but a much, much,
much bigger number.
•A mole is 602,000,000,000,000,000,000,000.
In words it is six hundred and two hexillion !
•Why is a mole so big? Because it is used to
count atoms and molecules which are very,
very, very small, It takes lots of them just to be
seen much less work with them. A speck of
dusk contains trillions of atoms or more!

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Counting Atoms and Molecules
•If atoms and molecules are so small and
numerous, how can they be counted??
•If atoms and molecules could be seen and all
the people on the earth began counting the
water molecules in our five teaspoons of water
and if everyone counted day and night for his
entire life, and if we added all their results
together we would still not count them all !!
•Counting atoms and molecules is difficult but
we have an easy way to count them.

6. How many marbles are
in the jar ?
How can we find out
without counting
them all ??
Suppose that we could
weigh a dozen
of the marbles and
we could also weigh
the marbles in the jar !
How would that help ?
Let’s pretend that the marbles in the jar
weigh 2000 grams and a dozen marbles
weigh 25 grams. Can you tell the
number of marbles in the jar ?

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COUNTING LARGE NUMBERS OF
SMALL THINGS
•In our marble example, the marbles weighed 2000
grams and one dozen of the marbles weighed 25
grams.
•Dividing 2000 grams (all the marbles) by 25 grams
(the weight of one dozen) gives 80 dozen marbles.
•Multiplying 80 times 12 we get 960 marbles in the
jar without actually counting all of the marble !
•In the case of atoms or molecules the same idea
can be used. If we know the weight of a number of a
certain type of atom or molecule and the weight of
the sample that we have we can then determine the
number of atoms or molecules in the sample by
division and multiplication.

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COUNTING LARGE NUMBERS OF
SMALL THINGS
•In counting atoms and molecules we will not use a dozen as
our counted quantity. A dozen atoms would be so small that
they could never even be seen with traditional microscopes.
•Our counted quantity will be one mole (6.02 x 1023 *) atoms or
molecules. Unlike our marble example we will not count out
and weigh the reference sample. Luckily, this work has been
done for us.
•The Periodic Table of the Elements lists the weight (mass) of
one mole of every element. We can find the weight of one
mole of each element in grams.
•* 6.02 x 1023 = 602,000,000,000,000,000,000,000 = 1 mole

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MOLES GRAMS
•MOLES GRAMS
•MULTIPLE BY GRAM MOLECULAR / ATOMIC WEIGHT*
•GRAMS MOLES
• DIVIDE BY GRAM MOLECULAR / ATOMIC WEIGHT
•* weight of one mole from the periodic table
How are the
number of moles
determined
from the number
of grams ?

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MOLES  ATOMS
•MOLES ATOMS
• multiply by 6.02 x 1023
•MOLES ATOMS
• divide by 6.02 x 1023
How are the
number of atoms
determined
from the number
of moles ?

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