Wake-up
1. Study Polyatomic Ions for about 5/10
minutes.
Write NO WAKE-UP on Friday
MOLAR MASS
What is molar mass?
How do you calculate molar mass?
Mole
The unit for a specific amount of a
substance/particle
Avogadro’s Number
1 mole = 6.02 x 1023 particles
Types of particles measured by Moles
Atoms, elements,
covalent compounds or
ionic compounds
Mole Road Map
Practice Problem
1. How many cadmium atoms are there in 6.57x103
moles?
Practice Problem
2. How many moles of nitrogen are there in
4.3x1023 molecules?
Mole Road Map
Moles to Mass
OR
Molar Mass
Molar Mass
The sum of the atomic weights of all the atoms in
a molecule
Molar Mass Units
Grams
Molar Mass (MM) =
(g/mol)
Moles
Use Periodic Table to determine MM
If there was one mole of Sodium (Na), it’s molar
mass would be ________________ g/mol.
• Carbon
• Mercury
• Iron
MM= 12.0 g / mol
MM= 200.6 g / mol
MM=55.8 g / mol
How many particles do these elements
contain?
Particles:
1. Atoms
2. Formula Units
3. Molecules
How do you calculate molar mass of
compounds?
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•
•
•
•
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SO
3
EX. Sulfur Trioxide Chemical Formula = ___________
How many total atoms make up one molecule?
1+3=4
Total Atoms = _____________
1 x ______
32.1 = 32.1
S: ___
16.0
3 x ______
O: ___
= 48.0
48.0
32.1
Molar Mass: __________
+ ____________
80.1
• The molar mass of sulfur trioxide = _______
g/mol
Your Turn
PCl3
• EX. Phosphorus Trichloride
Chemical Formula = _________
1+3=4
• How many total atoms make up one molecule? Atoms = _______
1 x ______
31.0
31.0 =
• P: ___
3 x ______
35.5 = _________
106.5 +
• Cl: ___
137.5 grams per 1 mol
• Sodium Hydrogen Carbonate
NaHCO3
MM = 84.0 g / mol
Conversions using Molar Mass
1. How many grams are in 4.5 moles of sodium
fluoride?
Conversions using Molar Mass
2. How many moles are in 3.4 x 10-7 grams of
silicon dioxide?
Conversions using Molar Mass
3. How many moles are in 68 grams of Copper (II)
hydroxide?
Conversions using Molar Mass
4. How many grams are in 2.3 x 10-4 moles of
Calcium phosphate?