The MOLE!
No, not the animal…Yes, this is chemistry
Know your targets!
• Students should be able to…
– Determine the molar mass of an element or
compound
– Use the factor-label method to convert between:
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Moles
Mass
Number of atoms or molecules
Volume of a gas
A What?!?
A mole is a unit!
A “mole” is a unit
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How many is a dozen? 12
How many is a baker’s dozen? 13
How many is a couple? 2
How many is a few? 3 or 4
How many is a decade? 10
How many is a mole?...the number of
particles (TBA) within a mole is always the
same regardless of the type of substance
When do we use moles?
• The Fed-Ex Story
– Moral?
• The Chuck E Cheese Story
– Moral?
Molar Mass
• Molar mass is the mass of one mole of any
element or compound.
• The molar mass for elements is found by looking
at the atomic masses on the Periodic Table.
• The units for molar mass are “grams per mole”
Compare Aluminum and Gold
Aluminum (Al)
Gold (Au)
Molar Mass= 27.0 g/mol
Molar Mass= 197.0
Molar Mass for Compounds
• Molar Masses are equal to the sums of the
molar masses of all atoms in one molecule of
that chemical compound
Ex. NaCl
Contains one atom of sodium and
one atom of chlorine.
(1 atom x 23.0 g/mole Na) + (1 atom x 35.5 g/mole Cl) = 58.5 g/mole NaCl
Molar Mass for Compounds
• A chemical formula with a subscript: Multiply
the atoms of anything next to the subscript
by the number of the subscript
Ex. FeCl2
contains one atom of iron and 2 of chlorine
(1 atom x 56 g/mole Fe) + (2 atoms x 35.5 g/mole of Cl) = 127 g/mole of FeCl2
Molar Mass for Compounds
O
• Other compounds:
O
N
Ex. Zn(NO3)2
O
Zn + NO3 + NO3
Zn + N + O + O + O + N + O + O + O
O
N
O
O
Contains one zinc atom, two nitrogen atoms, and six oxygen
atoms
(1 atom x 65 g/mole of Zn) + (2 atoms x 14 g/mole of N) + (6 atoms x 16 g/mole of O)
= 189 grams/mole of zinc nitrate
Molar Mass: Your Turn
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6.
Li
KOH
BF3
Mg(OH)2
H3PO4
(NH4)2SO4
Molar Mass: Answers
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6.
6.9 g/mol
56.1 g/mol
67.8 g/mol
58.3 g/mol
98.0 g/mol
132.1 g/mol