Avogadro’s Number
23
6.02x10
mole = (mol) 602000000000000000000000
Mole
• A mole is just a number like…
Pair = 2
Dozen = 12
Gross = 144
Century=100
Trio = 3
Baker’s dozen = 13
Score= 20
Ream=500
How BIG is a mole?
There are ~ 6.6 billion people on
Earth
How many Earths would it take to
equal the population
of 1 mole?
13
9.12 x 10
• If you spent $800 billion dollars a
day how many years would it take
to spend a MOLEion dollars?
9
2.06 x 10 years
• If you had a mole of cats . . .
They would create a sphere
larger than
Earth!
• If you had a mole of H2O
could you swim in it?
NO! 
Water molecules are so small
that a mole of H2O = 18ml
• In chemistry we don’t work with
individual atoms or molecules because
they are too small to be weighed or
measured
• We have to work with LOTS of atoms in
order to measure them
THAT’s WHERE THE
MOLE COMES IN!
How small are atoms?
• There are more atoms in one
gram of salt than grains of
sand on all the beaches
of all the oceans in all
the world.
Gram ATOMic Mass
• mass is in grams of 1 mole of
atoms of an element
• In other words……
23
1 mol C atoms = 6.02 x 10 C
atoms = 12g C
Practice
Remember . . .
1 mole = 6.02x1023 atoms or molecules
= ______ g from the periodic table
Stoichiometry of
Chemical Formulas
Gram Formula Mass
Gram Molecular Mass
Molar Mass
• mass in grams of 1 mole of a substance
• In other words . . . Add it all up!
1 mole of NaCl = 58g = 6.02x1023 particles of NaCl
1 mole of H2O = 18g = 6.02x1023 molecules of H20
Now…..
• Use the gram formula mass and the
gram atomic mass to determine
– how many moles or atoms of an element are
found in some mass of a substance
– how much mass that element contributes to
the mass of the entire substance
Use factor label & follow the units!
Stoichiometry of Chemical Formulas
• If you have 1 molecule of (NH4)2SO4
– How many atoms of N are there?
– How many atoms of H?
SO…..
• If you have 1 mole of of (NH4)2SO4
– How many moles of N are there?
– How many moles of H?
Practice
Remember . . .
23
1 mole = 6.02x10 atoms or molecules
= ______ gfm from the pt
Molar Volume
• 1 mole of ANY gas
Gases ONLY
O2 (g)
@STP
NH3 (g)
He (g)
contains 6.02 x 1023 molecules and
occupies a volume of 22.4L
• STP
standard temperature & pressure
0oC or 273K
101.3kPa or 1 atm
Remember . . .
• Gases also have mass
1 mole of O2(g) = 32g
1 mole of NH3(g) = 17g
 we can calculate
Density!
m
D= /
v
• A sample of oxygen contains 3 moles
of particles at STP what is its density?
• 2 steps
– Convert moles to mass AND volume
– Calculate density
• If mass or volume is given, use it and
convert the other……. THEN calculate D!
Remember . . .
1 mole =
23
6.02x10 atoms or molecules =
22.4L (g)
gfm =
Stoichiometry of Chemical
Equations
• The study of quantitative relationships that
can be derived from chemical equations.
“it’s a simple matter
of weight ratios . . .”
Stoichiometry cookies
• If you look at chemical equations as
recipes it may be easier to understand
that
– changing the amount of a reactant will
change the amount of the product IN THE
SAME RATIO!
Examining Molar Relationships in
Balanced Equations
6CO2 + 12 H2O + 2804kJ  6O2 + C6H12O6 +6H20
Balanced equations
– Law of conservation of mass / matter
• ATOMS are not created or destroyed during a
chemical reaction, they are only rearranged to form
new substances.
• # atoms on reactant side = # atoms on product side
– Law of conservation of E
• E on the reactant side = E on the product side
Mole - Mole Relationships
Practice
The End