What’s up with the
Mole?
How do we measure matter?
By weight:
pound
We buy bananas by the _______________.
By volume:
gallon
Milk is sold by the ____________________.
By counting:
There are ________ students in class.
Chemical Quantities
Many words are used to express a specific quantity.

Pair = 2

Dozen = 12
How do we measure matter?
•
What if I wanted to know how many ATOMS
were in this copper penny? Would you like
to count? Could you?
Avogadro’s Number
• You can count particles if you introduce a term
that represents a specified number of particles.
• In chemistry, the term used to express a specific
number of particles is a mole.
Avogadro’s Number
• 1 mole = 6.02 x 1023 particles
• That’s 602,000,000,000,000,000,000,000
• A very large number!
Avogadro’s Number
This number is known
as Avogadro’s number,
named after Amedeo
Avogadro (an Italian
physicist and
mathematician).

1 mole of hockey pucks would equal the mass of
the moon!

1 mole of pennies would cover the Earth 1/4 mile
deep!
Representative Particles
Representative particles are units used to
measure the number of particles in a sample of
an element or compound.
Substance
Representative
Particle
element
atom
covalent compound
molecule
ionic compound
formula unit
Representative Particles
What is the representative particle for each of these
substances?
• copper
atom
• sodium chloride formula unit
• water
molecule
MOLE
• A mole is the SI unit that measures the
amount of a substance.
• A mole can be related to:
• number of particles
• mass
• volume of a gas
one mole
Avogadro’s
number of
particles
mass in grams
using the
periodic table
22.4 L of a gas
MOLE
• Use dimensional analysis to convert:
– moles to molecules
– moles to atoms
– moles to formula units
– moles to grams
– grams to atoms
– and many more….
MOLE
When converting between moles and particles,
the conversion factor to remember is:
1 mol = 6.02 x 1023 particles
The particle unit can be atoms, molecules, or
formula units.
Mole/Particle Examples
1. How many moles are in 3.25 X 1020 atoms of
lead?
1 mol = 6.02 x 1023 atoms
3.25 x 1020 atoms Pb
1 mol Pb
6.02 x 1023 atoms Pb
= 5.398671 x 10-4 = 5.40 x 10-4 mol Pb
Mole/Particle Examples
2. How many molecules are there in 8.3 moles
of sugar (C12H22O11)?
1 mol = 6.02 x 1023 molecules
8.3 mol C12H22O11 6.02 x 1023 molec. C12H22O11
1 mol C12H22O11
= 4.9966 x 1024 = 5.0 x 1024 molec. C12H22O11
Mole/Particle Examples
3. How many atoms are in 0.425 mol sulfur?
1 mol = 6.02 x 1023 atoms
0.425 mol S
6.02 x 1023 atoms S
1 mol S
= 2.5585 x 1023
= 2.56 x 1023 atoms of S
Mole/Particle Examples
4. How many moles are in 5.42 x 1022 formula
units of NaCl?
1 mol = 6.02 x 1023 atoms
5.42 x 1022 Form. U NaCl
1 mol NaCl
6.02 x 1023 Form. U NaCl
= 0.090033222 = 0.0900 mol NaCl
Molar Mass
molar mass – the mass in grams of one mole of
an element or compound.
Terms that Describe the
Mass of a Substance
• Atomic mass – mass of one atom of an element
(unit = amu)
• Molecular mass - mass of one molecule of a
covalent compound (unit = amu)
• Formula mass - mass of one formula unit of an
ionic compound (unit = amu)
• Molar mass - mass of one mole of an element
or compound (unit = g/mol).
Molar Mass
To calculate molar mass:
1. Obtain all of the masses of the involved
elements from the periodic table.
2. Multiply each element’s mass by the subscript.
3. Add the resulting products.
4. Round the answer to the proper number of
decimal places.
Molar Mass of Element Examples
• Aluminum = 26.982 = 26.98 g/mol
• Zinc = 65.38 g/mol
Molar Mass of Compounds Examples
• Diphosphorus pentaoxide
P2O5
P = 30.974 X 2 = 61.948
O = 15.999 X 5 = 79.995 +
141.943 = 141.94 g/mol
Molar Mass of Compounds Examples
+3
-1
• Aluminum Hydroxide
Al(OH)3
Al = 26.982 X 1 = 26.982
O = 15.999 X 3 = 47.997
H = 1.008 X 3 = 3.024 +
78.003 = 78.00 g/mol
Molar Mass of Compounds
Examples
+2
-3
• Barium phosphate
Ba3(PO4)2
Ba = 137.328 X 3 = 411.984
P = 30.974 X 2 = 61.948
O = 15.999 X 8 = 127.992 +
601.924 = 601.92 g/mol
Moles to Mass
• Use dimensional analysis to convert
– moles to mass or mass to moles.
• Mass unit = grams
• Conversion Factor to Remember:
– 1 mol = molar mass of the element or compound
(molar mass = g/mol) found on the periodic table
Moles to Mass Examples
• How many moles of carbon are in 26 g of
carbon?
Carbon: 1 mol = 12.01 g (from PT)
26 g of C
1 mol of C
12.01 g of C
= 2.164862614
= 2.2 mol of C
Moles to Mass Examples
• How many grams are there in 2.37 moles of
CO2?
C = 12.011 x 1 = 12.011
O = 15.999 x 2 = 31.998 +
44.009 g = 1 mol
2.37 mol CO2 44.01 g CO2
1 mol CO2
= 104.3037
= 104 g CO2
Moles to Mass Examples
• How many moles are present in 142.1
grams of NaCl?
Na = 22.990 x 1 = 22.990
Cl = 35.453 x 1 = 35.453 +
58.443 g = 1 mol
142.1 g NaCl
1 mol NaCl
= 2.43155373
58.44 g NaCl
= 2.432 mol NaCl
Moles to Mass Examples
• How many grams are in 3.34 moles of
+1
-1
potassium bromide? KBr
K = 39.098 x 1 = 39.098
Br = 79.904 x 1 = 79.904 +
119.002 g = 1 mol
3.34 mol KBr 119.00 g KBr
= 397.46 = 397 g KBr
1 mol KBr
Molar Volume of a Gas
• The volume of a gas changes as the
temperature and pressure change, so the
volume is usually measured at standard
temperature and pressure.
• STP = abbreviation for standard temperature
and pressure
• Standard temperature = 0oC = 273 K
• Standard pressure = 1 atm or 101.3 kPa
Molar Volume of a Gas
• At STP, one mole of any gas occupies the same
volume: 22.4 L.
Molar Volume of a Gas
• Use dimensional analysis to convert:
– volume (liters) to moles
– or moles to volume (liters)
• Conversion Factor to Remember:
– 1 mole = 22.4 L
Molar Volume of a Gas
Examples
• Determine the volume, in liters, of 0.60 mol
SO2 gas at STP.
Molar Volume of a Gas
Examples
• Assuming STP, how many moles are in 67.2 L
SO2?
Molar Volume of a Gas
Examples
• How many moles are in 1.0 x 103 L of C2H6?
Molar Volume of a Gas
Examples
• What is the volume at STP of 3.20 x10-3 mol
CO2?
Mole Calculations Learned
# of Particles
(atoms,
molecules,
formula units)
1 mol =
6.02 x 1023
particles
MOLES
1 mol = 22.4 L
1 mol = mass from
Periodic Table
Mass
(grams)
Liters of gas
at STP