1. Unit 7: Stoichiometry Mrs. Callender
The Mole - Part II
Unit 7: Stoichiometry
Mrs. Callender

2. Lesson Essential Questions
How do I convert moles to mass, volume, atoms and molecules?

3. Mole Map Grams Volume of a Gas mole Atoms (element) atoms molecules
@ STP
22.4 L
mole
6.02 x 1023
6.02 x 1023
Atoms (element)
# atoms per molecule
atoms
molecules

4. Factor Label – It’s back…..
How many moles are in 45.7 g of NO2?
Ask yourself the question – Can I convert directly from grams to moles?
Molar mass = g + 2(16.00 g) = g
5. Use conversion factor that will allow you to “cancel” out grams and give you moles.
Cancel out units and calculate using
significant digits.
4. Start with your “given” from the original problem.
YES – molar mass has a unit of
grams/mole
3. Form conversion factors.
2. Calculate Molar Mass of NO2.
1 mole
46.01 g 7 N 8 O
46.01 g
1 mole
Molar mass =
14.01 g + 2(16.00 g) = g
1 mole
45.7 g NO2 1 x =
0.993 mole NO2
46.01 g NO2

5. Factor Label – It’s back…..
How many atoms are in moles of Iron (Fe)?
5. Use conversion factor that will allow you to “cancel” out moles and give you atoms.
Cancel out units and calculate using
significant digits.
4. Start with your “given” from the original problem.
Ask yourself the question – Can I convert directly from moles to atoms?
YES – there are
6.02 x 1023 atoms = 1 mole
3. Form conversion factors.
1 m0le
6.02 x 1023 atoms
6.02 x 1023 atoms
1 mole
6.02 x 1023 Fe atoms
10.0 moles Fe 1 x =
6.02 x 1024 Fe atoms
1 mole Fe

6. Factor Label – It’s back…..
How many molecules are in 12.1 g of H2SO4?
Molar mass = 2(1.00)g g + 4(16.00) g = g.
Ask yourself the question – Can I convert directly from grams to molecules?
NO – You will need two conversion factors. Grams to moles and moles to molecules.
Use conversion factors that will allow you to
“cancel” out grams and give you moles and moles
to give you molecules.
Cancel out units and calculate using
significant digits.
4. Start with your “given” from the original problem.
2. Calculate Molar Mass of H2SO4.
3. Form conversion factors.
Molar mass =
2(1.01) (16.00 g) = g 1 H 16 S
32.066 8 O
1 mole
98.09 g
98.09 g
1 mole
1 mole
6.02 x 1023 molecules
6.02 x 1023 molecules
1 mole
6.02 x 1023 molecules
12.1 g H2SO4 1
1 mole = x x
98.09 g H2SO4
1 mole
7.42 x 1022 molecules H2SO4

7. Factor Label – It’s back…..
How many atoms are in g of H2SO4?
Molar mass = 2(1.00)g g + 4(16.00) g = g.
Ask yourself the question – Can I convert directly from grams to atoms for a molecule?
Count the number of atoms in one molecule of sulfuric acid.
How do we go from molecules to atoms?
Use conversion factors that will allow you to
“cancel” out grams and give you moles and moles
to give you molecules.
4. Start with your “given” from the original problem.
NO – You will need three conversion factors. Grams to moles, moles to molecules and molecule to atoms.
2. Calculate Molar Mass of H2SO4.
3. Form conversion factors.
Cancel out units and calculate using
significant digits.
2H + 1 S + 4 O = 7 atoms in 1 molecule of H2SO4 so…..
1 molecule H2SO4
7 atoms
7 atoms
1 molecule H2SO4
Molar mass =
2(1.01) (16.00 g) = g 1 H 16 S
32.066 8 O
1 mole
98.09 g
98.09 g
1 mole
1 mole
6.02 x 1023 molecules
6.02 x 1023 molecules
1 mole
210.0 g H2SO4 1 x
1 mole
6.02 x 1023 molecules
7 atoms H2SO4 x x =
98.09 g H2SO4
1 mole
1 molecule H2SO4
9.022 x 1024 atoms H2SO4

8. What conditions need to exist to use the conversion 1 mole – 22.4 L?
Standard Temperature and Pressure - STP
Standard Temperature
0 oC
1 atm or 760 torr or KPa
Standard Pressure
At these conditions 1 mole of any gas has a volume of 22.4 L.
*We will learn how to convert gases at other conditions in the Gas Law Unit.

9. Factor Label – It’s back…..
How many molecules are in 15.7 L of carbon monoxide?
NO – you will need two conversion factors. Liters to mole and mole to molecules
Ask yourself the question – Can I convert directly from liters to molecules?
4. Use conversion factor that will allow you to “cancel out moles and give you atoms.
5. Cancel out units and calculate using
significant digits.
3. Start with your “given” from the original problem.
2. Form conversion factors.
1 m0le
6.02 x 1023 molecules
6.02 x 1023 molecules
1 mole
1 mole
22.4 L
22.4 L
1 mole
1 mole CO
6.02 x 1023 molecules CO =
15.7 L CO 1 x x
22.4 L CO
1 mole CO
4.22 x 1023 CO molecules