The Mole
It's not a spy, a machine for digging tunnels, a burrowing animal,
or a spot of skin pigmentation - it's
- a unit of measurement containing about
6.02 x
23
10
particles.
1 dozen atoms is
12 atoms!
1 pair of atoms is
2 atoms!
1 gross of atoms is
144 atoms!
1 mole of atoms is
602,214,199,000,000,000,000,000 atoms!
Avogadro’s Number
(NA)
6.022 x 1023 particles / mole
Amadeo Avogadro
1776-1856
How BIG is 6.022 x 1023 ?
Could Bill Gates ever become
a “moleonaire”?
How much interest would you get per
second if 1 mole of $ was invested at an
annual interest rate of 1%
• 6.02 x 1023$ x (1/100) = 6.02 x 1021$ (1 year)
• 6.02 x 1021$ / 365 days = 1.65 x 1019$ (1
day)
• 1.65 x 1019$ / 24 hours = 6.87 x 1017$ (1
hour)
• 6.87 x 1017$ / 60 min = 1.15 x 1016$ (1 min)
• 1.15 x 1016$ / 60 sec = 1.90 x 1014$ (1 sec)
190 TRILLIONS per SECOND !
Bill Gates only currently has
70 billion $ (70 x 109 $)
1 second of interest (at 1%)
on a mole of $ is equivalent to
3000 times Bill’s Gates total
wealth!
To become a moleonaire Bill
Gates would have to earn
33,000 trillion $ a day for the
next 50 years!
Not likely!
Too bad Bill! Soooo sad…
The Pacific Ocean
How much water is there in the
Pacific Ocean?
• Approximately 6 x 1020 L
• which is equivalent to 6 x 1023 mL !
• The Pacific Ocean contains a mole of mL
of water
A Galactic Analogy
• A mole of periods (.) lined up side by side
would equal the radius of our galaxy
(30,000 light years!)
A mole is big…
real big.
But is it really that
important?
Yes. Why?
Importance of the Mole
• Scientists use the mole to help count atoms,
molecules, and compounds
– Example:
• 0.5 Moles of CO2 = 3.01x1023 Molecules of CO2
• 0.25 Moles of Carbon = 1.5x1023 atoms of Carbon
• How many molecules are there in 2.0 moles of O2?
6.02 ´10 23 molecules
2.0moles ´
= 1.2 ´10 24 molecules
1.0mole
• How many ATOMS are there in 2.0 moles of O2?
– 2.4 x 1024 Atoms of Oxygen
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What is Avogadro’s Number?
If I had a half-dozen eggs how many
would I have?
If I had a half-mole of eggs how many
would I have?
If I had a half-mole of copper atoms
how many would I have?
Importance of the Mole
• Practice
– How many molecules are in 5.0 moles of
NO2?
– How many atoms are there in 0.25 moles of
Sulfur?
– How many molecules are there in 7.6 moles
of C2O4?
– How many ATOMS are there in 7.6 moles of
C2O4?
Importance of the Mole
• Moles tell us how many particles there are of
something.
– Example:
• 1.0 moles of Sodium atoms = 6.02x1023 atoms of Sodium
• A mole is a big number… what do you suppose
the mass of one mole of sodium atoms is?
– 23.0 grams!
• Golly-gee-whilickers! How did you find that out?
• Hmmm…
!!!THE PERIODIC TABLE!!!
Moles of atoms
• Off the Periodic Table:
– 1 mole C = 12.011 g C
– 1 mole B = 10.81 g B
– 1 mole Cu = 63.55 g Cu
– 1 mole element = (atomic mass) g element
• We can then say that ….
Moles=grams / molar mass
• This is useful information! Watch!
Aluminum Can Lab
• How many moles of
Aluminum (Al) are in
an aluminum can?
• How many atoms of
Aluminum (Al) are in
an aluminum can?
Importance of the Mole
• Scientists can use the mole to determine how
many particles are in a sample.
– Example:
• If you have 5 grams of water,
how many water molecules
do you have?
– 1st we need to determine the Molar Mass for Water
How do I find Molar Mass you
Ask?
• Determine the formula
for the molecule.
– EX. Water is Dihydrogen
Monoxide
• H 2O
• Find the molar mass
for each atom in the
molecule.
– H = 1.008 g/mole
– O = 15.994 g/mole
But Wait!!
• There are two hydrogen atoms in a molecule of
water, so…
– 2H = (1.008 g/mole) X 2 = 2.016 g/mole H
• Now that I know the molar mass
for the atoms in water,
I can calculate the formula
mass for water:
2.016 g/mole H
+ 15.994 g/mole O
18.01 g/mole H2O
In Summary: Mole Formulas
(You need to know these!)
• Moles * Molar mass = Mass of Sample
– (I write it as Moles*MU = MG)
– Moles is how many moles you have
– Unit Mass is the mass of whatever unit you are
dealing with (atoms, molecules, etc)
– Mass of Sample is the mass of your sample
• Moles =NP/NA
– NP = Number of particles (how many atoms,
molecules, etc. your sample contains)
– NA=Avogadro’s Number