Mole Gangnam Style
https://www.youtube.com/watch?v=HnRHBw-xjVo
Grams
# ions per
formula unit
formula
unit
6.02 x 1023
Mr
mole
6.02 x 1023
Mole Map
atoms
molecules
# atoms per
molecule
Atoms
(element)
Dimensional Analysis
How many moles are in 45.7 g of NO2?
1.
Ask yourself the question – Can I convert directly
from grams to moles?
YES – molar mass has units of grams/mole
Molar mass NO2 = 14.007 g + 2(15.999 g) = 46.005 g/mol
2. Start with your “given” from the original problem.
3. Use conversion factor that will allow you to “cancel” out
grams and give you moles.
4. Calculate & express answer
with correct sig. figs. and units!
45.7 g of NO2 1 mol
46.005 g
= 0.993 mol
Dimensional Analysis
How many atoms are in 10.0 moles of Iron (Fe)?
1.
Ask yourself the question – Can I convert directly
from moles to atoms of an element?
YES – there are 6.02 x 1023 atoms per mole
2. Start with your “given” from the original problem.
3. Use conversion factor that will allow you to “cancel” out
grams and give you moles.
4. Calculate & express answer with correct sig. figs. and units!
10.0 mol Fe
6.02 x 1023 atoms Fe
1 mol Fe
= 6.02 x 1024 Fe atoms
Dimensional Analysis
How many molecules are in 12.1 g of H2SO4?
1.
Ask yourself the question – Can I convert directly
from grams to molecules?
NO– I have to go through moles
2. Start with your “given” from the original problem.
3. Use conversion factor that will allow you to “cancel” out
grams and give you moles.
4. Calculate & express answer with correct sig. figs. and units!
12.1 g H2SO4
1 mol
6.02 x 1023 molecules
98.078 g
1 mol
= 7.37 x 1022 molecules
Dimensional Analysis
How many atoms are in 210.0 g of H2SO4?
NOTE: How many atoms are in 1 molecule of H2SO4?
2H + 1S + 4O = 7 total atoms per molecule
210.0 g H2SO4 1 mol
98.078 g
6.02 x 1023 molecules
1 mol
7 atoms
1 molecule H2SO4
= 9.023 x 1024 atoms
Dimensional Analysis
How many formula units are in 32.6 grams of
potassium oxide?
What is the formula for potassium oxide?
32.6 g K2O
1 mol
94.195 g
K 2O
6.02 x 1023 f. units
1 mol
= 2.08 x 1023 formula units
Dimensional Analysis
How many lithium ions are in 125g of lithium
sulfate?
What is the formula for lithium sulfate?
Li2SO4
How many lithium ions are in one formula unit? 2
125 g Li2SO4
1 mol
109.944 g
2 Li ions
6.02 x 1023 f. units
1 mol
1 f. unit Li2SO4
= 1.37 x 1024 Li ions