THE MOLE
... a unit of counting
Quantities in Chemical Reactions
Big Ideas

Relationships in chemical reactions can be
described quantitatively

The efficiency of chemical reactions can be
determined and optimized by applying an
understanding of quantitative relationships
in such reactions.
Today

How do chemists calculate and express the
number of atoms or molecules in a
substance?

How many atoms are in a 27g piece of
aluminium foil? Take a guess
How Scientists Keep Track of Atoms
• One way to measure how much of
a substance is available is to count
the # of particles in that sample
• However, atoms & molecules are
extremely small
• To solve this problem, scientists
developed the concept of the mole
• SYMBOL IS n .
•*The mole is a unit song
The Mole
A dozen donuts = 12
 A mole of donuts = 6.023x1023

a dozen shoes = 12
 A mole of shoes = 6.023x1023

1 mole = 6.02 x 1023 entities of a
substance
 1 mole of anything = 6.023x1023
= 602,000,000,000,000,000,000,000!!!

WHAT IS THE MOLE?
FYI….
A formula unit is
a term used to
represent the
lowest whole
number ratio of
ions in an ionic
compound.
Different types of particles include:
atoms OR molecules OR ions OR
electrons OR formula units, etc.
Avogadro’s Constant = NA
= 6.023 x 1023 particles
1 mol
Units of moles are mol
On your calculator:
EE or EXP or x10^
WHERE DID THIS NUMBER
COME FROM?
A mole is the amount of substance
that contains as many particles as
exactly 12.000g of Carbon-12
The Mole- Examples

1 mole of carbon contains 6.02 x
1023 atoms of carbon

1 mole of H2O contains 6.02 x 1023
molecules of H2O

1 mole of NaCl contains 6.02 x 1023
formula units of NaCl
How Big is Avogadro’s
Number?
If you had one mole of dollars,
how long would it take to spend it
at a rate of $1,000,000 per day?
◦
o
6.02 x 1023 ÷ 1,000,000 = 6.02 x 1017 d
6.02 x 1017 d ÷ 365 d/a = 1.65 x 1015 a
Put this into perspective…
o The sun is about 4.6 x 109 years old and will burn out in
about 5 x 109 years.
o You will need to spend faster!!
Just How Big is a Mole?



Enough soft drink cans to cover the
surface of the earth to a depth of
over 200 miles.
If you had Avogadro's number of
unpopped popcorn kernels, and
spread them across the United
States of America, the country would
be covered in popcorn to a depth of
over 9 miles.
If we were able to count atoms at the
rate of 10 million per second, it
would take about 2 billion years to
count the atoms in one mole.
The mole is a BIG number.

The green pea analogy puts it into
perspective as well:

Did you know that 12 pencils will contain
a mole of carbon atoms?
Learning Check
Suppose we invented a new collection unit
called a trapp. One trapp contains 8 objects.
1. How many paper clips in 1 trapp?
a) 1
b) 4
c) 8
2. How many oranges in 2.0 trapp?
a) 4
b) 8
c) 16
3. How many trapps contain 40 gummy
bears?
a) 5
b) 10
c) 20

1. Volume of 1 mol of peas
-need to look it up or measure with water
displacement/math 
Vpea = 0.2mL
V mol pea = 0.2mL x 6.023 . 1023
don’t forget to convert units. In
this case mL to L
2. Google
 3. Divide

Vocean = …..
…L/….L
How many times would 1 mole of
green peas fill the Atlantic ocean?
Variables to Know
N
•
•
•
n = number of moles
n
NA
N = number of particles
NA = Avogadro’s number (6.02 × 1023)
•
Two possible types of questions:
o
Moles to Particles

o
N = n x NA
Particles to Moles

n = N / NA
Using Avogadro’s Constant
•
•
How many atoms in 2
moles of carbon?
N = n x NA
= 2 moles x (6.02 x
1023)
= 1.2 x 1024 particles
of C
How many moles is 5.0 x
1024 particles of iron?
n = N / NA
= 5.0 x 1024/6.02 x
1023
= 8.3 moles of Fe
•
How many atoms in 2 moles of
water?
N = n x NA
= 2 moles x 6.02 x 1023
= 1.2 x 1024 molecules of
H2O
= 3 atoms per molecule
= 3 x (1.2 x 1024 )
= 3.6 x 1024 atoms in 2
moles of H2O
LEARNING CHECK (round to 3 sig. figs.)
 How many molecules of CO2 are in
4.56 moles of CO2? 2.75 x 10 molecules
 How many moles of water is 5.87 x
1022 molecules? 0.0975 mol (or 9.75 x 10 )
 How many moles is 7.7812.9xmoles
1024
formula units of MgCl2
4.44 x 10 atoms
C
 How many atoms of carbon
are
in
1.23 mol of C6H12O6?
 Try another…
24
-2
24
 How many electrons are in 1.5 mol of CO2?
Size of a Mole Assignment
To better understand the immensity of the
mole you will compare a mole of
something to a mole of something else
that can be pictured…. BE CREATIVE!!
Eg. Mass of one
How much honey would one mole of bees
mole of a
substance
produce in one season compared to the
mass of water in the Atlantic Ocean?
Time to
complete one
mole of a task
How long would it take in years to blink
6.023 x 1023 times?
Volume of a
substance
If you had a mole of green peas covering
the earth, how deep would the layer be?
There are 3 parts to this
assignment:
Pick a unique question that compares 1
mole of something to another thing that
can be seen visually.
2. Perform the correct calculations
3. Make a picture to show the size
comparison
4. 1 min presentation
1.
Rubric
Level 4
Unique Question that
compares 2 things that can
be pictured [A-10]
•Question is
unique
•The entities
compared are
easily pictured
Calculations are correct
and show the size
comparison [I-10]
Calculations use GRASP &
have units [I-10]
•All calculations
are correct
•All units included
•All work logically
shown (GRASP)
Picture is creative and
shows the size comparison
well [C-10]
Presented well
•Neat and
attractive picture
•Size comparison
is clear.
Level 3
Level 2
Level 1
Mass to Mole Calculations

Atomic Mass
◦ Mass of one atom
◦ Unit μ = atomic mass unit = a.m.u
 Eg. Each hydrogen atom has a mass of 1.001μ
◦ 1 μ equals approximately 1.67 x 10-24g, which
is extremely small and not practical to measure.

Enter Molar Mass….
Molar Mass (MM)

The mass of 1 mole of a substance

Mass of 6.023 x 1023 particles

Units are g/mol
◦ Eg. The molar mass of Hydrogen is 1.01 g/mol
Molar Mass

Molar mass and atomic mass have the
same numbers except there is a unit
difference.
Atomic Mass

Molar Mass
Li
6.94 μ/atom
6.94 g/mol
Ag
107.86 μ/atom
107.86 g/mol
The g/mol unit is more useful that μ
because…
It can be measured in the lab using a scale

Eg. Find the molar mass of water:
H2O
H: 2 x 1.001g/mol
O: 1 x 16.00 g/mol
18.002g/mol
Eg. Find the molar mass of calcium
phosphate:
Ca3(PO4)2
Ca: 3 x 40.08
g/mol
P:
2 x 30.97 g/mol
O: 8 x 16.00 g/mol
310.2g/mol

The same as:
Gram Molecular Mass (for molecules)
Gram Formula Mass (ionic
compounds)
 Gram Atomic Mass (for elements)
 molar mass is just a much broader
term than these other specific masses
Complete the following chart

**because this is a chart and not a table you can include
units and calculations in the boxes.
Substanc
e
Ne
O3
C6H12O6
KClO3
Pb
NH3
LiBr
Type of Particle
(atom, molecule,
formula unit etc.)
Mass of 6.023 x
1023 particles
(Molar Mass)
Atomic Mass (μ)
1 Mole in a Beaker Activity

Calculate the mass of one mole of each substance. Show your calculations in the
boxes below. Measure out one mole of each substance into a 400mL beaker and draw
a line on the beaker in the table to show how much space one mole of that substance
takes up.
1 mole of Cu
1 mole of Pb
1 mole of NaCl
1 mole of C12H22O11
1 mole of H2O
1 mole of C
Mole Calculations
MM = m/n
m
n = m/MM
MM
n
m = MMn
Factor Label!
Let the units guide you
N = nNA
n = N/NA
Converting between Mass and
Mole
HOMEWORK
pp. 232
#1, 4, 5, 7, 8, 11,
15
Quiz tomorrow
– one question from
homework.
A mole is a unit