THE “MOLE” - NOTES
Standard C-4: Apply the concept of moles to determine the number of particles of a substance in a chemical reaction, the percent composition of a representative
compound, the mass proportions, and the mole-mass relationships.
Notes/Q’s
Objective: By the end of this lesson I will be able to explain the “mole,” “molar mass,” and “Avogadro’s number.” I will also use these concepts
to do the following conversions:
Appetizer:
# particles
moles
moles
mass (g)
mass (g)
How do we count atom, molecule, and formula units?
1.Take a guess of how many
items are in the container. __________
2. How many atoms of
copper do you think
there are in 63.546 g
of copper wire?
# particles
We use the ______________.
What is the mole?
n
The amount of substance that contains as many particles as there
are atoms in exactly 12 g of carbon-12.
n
A counting number (like a dozen or a pair)
n
Avogadro’s number (NA) (6.022  1023) or (6.022 E23)
____________________________________________________
n
1 mole = 6.022  1023 items (of anything)
____________________________________________________
n
Abbreviation = “mol”
n
Variable = “n”
___________
3. Discuss with the person beside you whether a single dozen of
different items would have the same mass._________________
Molar Mass
Examples:
1 dozen
# of
Pumpkins
12
1 mol
# of
Pumpkins
6.022 E23
5 dozen
(5 x12)
1.5 dozen
(1.5 x 12)
60
18
5 mol
5 x (6.022 E23)
1.5 mol
1.5 x (6.022 E23)
3.011 E24
9.033 E23
1 mole of hockey pucks would equal the mass of the moon!
1 mole of basketballs would fill a bag the size of the earth!
1 mole of pennies would cover the Earth 1/4 mile deep!
n
Molar mass = mass of 1 mole of an element or compound.
n
Atomic mass on the P.T. tells the...
 atomic mass units per atom (amu)
 grams per mole (g/mol)
 Ex: 6.022 E23 C atoms = 1 mol C atoms = 12.011g C
Examples:
Substance
Molar mass
Aluminum
26.982 g/mol
Zinc
65.409 g/mol
1 mol C =
12.011 g
*Simply look at the atomic mass on the P.T. This is also equal to the molar
mass of that element.
THE “MOLE” - NOTES
Molar Mass of Compounds
Notes/Q’s
n
n
Ex: Magnesium Acetate
Formula = Mg(C2H3O2)2
The molar mass of a compound is equal to the sum of all the element’s molar masses in the compound.
Mg =
H=
Chemical Formula – a combination of symbols and numbers to represent a substance.
 Subscripts right after a symbol indicates the number of atoms in that compound.
C=
O=
 If no subscript is written, you assume “1.”
 Subscripts right after parentheses apply to everything in parentheses. (multiply each subscript by the subscript outside
parentheses.
Name
Formula
Water
H2O
Sodium Bicarbonate
NaHCO3
Magnesium Acetate
Mg(C2H3O2)2
Sucrose
C12H22O11
Calculation
Molar Mass =
Molar Conversions #1
How many moles of carbon are in 26 g of carbon?
Molar Conversions #2
How many molecules are in 2.50 moles of C12H22O11?
Molar Conversions #3
Molar Conversions #4
Find the mass of 2.1  1024 molecules of NaHCO3.
Find the # of oxygen atoms in 5.00 grams of NaHCO3.