Stoichiometry
2 slices bread + 1 slice ham  1 ham sandwich
What is stoichiometry?
Comes from the Greek words stoicheion, meaning
element and metron, meaning measure.
In the real world, chemists perform reactions to make
useful chemical compounds such as medicines,
fibers, pigments, cosmetics and structural materials.
Because some reactants are expensive chemists don’t
just mix huge quantities of chemicals together and
hope for the best; rather they use stoichiometry to
calculate the mass relationships between products
and reactants.
Mole Ratios
Mole ratios are the key to stoichiometric
calculations.
They give us the ratios between the
amounts of reactants and products in any
given reaction.
We get mole ratios from the coefficients.
That’s why we need to start with a balanced
equation.
Mole Ratios
Start with a
balanced
equation
The coefficients
represent moles
Divide one
coefficient by
the other to get
the mole ratio
Mole Ratios
2 slices
bread
1 slice
ham
What is the mole ratio of bread slices to ham slices?
1 ham
sandwich
Mole Ratios
2 slices
bread
1 slice
ham
What is the mole ratio of bread slices to ham slices?
1 ham
sandwich
2/1
Mole Ratios
2 slices
bread
1 slice
ham
1 ham
sandwich
What is the mole ratio of bread slices to ham slices?
What is the mole ratio of ham slices to ham sandwiches?
2/1
Mole Ratios
2 slices
bread
1 slice
ham
1 ham
sandwich
What is the mole ratio of bread slices to ham slices?
2/1
What is the mole ratio of ham slices to ham sandwiches?
1/1
Mole Ratios
2 slices
bread
1 slice
ham
1 ham
sandwich
What is the mole ratio of bread slices to ham slices?
2/1
What is the mole ratio of ham slices to ham sandwiches?
1/1
What is the mole ratio of ham sandwiches to bread slices?
Mole Ratios
2 slices
bread
1 slice
ham
1 ham
sandwich
What is the mole ratio of bread slices to ham slices?
2/1
What is the mole ratio of ham slices to ham sandwiches?
1/1
What is the mole ratio of ham sandwiches to bread slices? 1/2
Mole Ratios
C3H8
5O2
•What is the mole ratio of propane to oxygen?
3CO2
4H2O
Mole Ratios
C3H8
5O2
•What is the mole ratio of propane to oxygen?
3CO2
4H2O
1/5
Mole Ratios
C3H8
5O2
3CO2
•What is the mole ratio of propane to oxygen?
•What is the mole ratio of propane to carbon dioxide?
4H2O
1/5
Mole Ratios
C3H8
5O2
3CO2
•What is the mole ratio of propane to oxygen?
•What is the mole ratio of propane to carbon dioxide?
4H2O
1/5
1/3
Mole Ratios
C3H8
5O2
3CO2
•What is the mole ratio of propane to oxygen?
•What is the mole ratio of propane to carbon dioxide?
•What is the mole ratio of oxygen to water?
4H2O
1/5
1/3
Mole Ratios
C3H8
5O2
3CO2
•What is the mole ratio of propane to oxygen?
•What is the mole ratio of propane to carbon dioxide?
•What is the mole ratio of oxygen to water?
4H2O
1/5
1/3
5/4
Mole Ratios
C3H8
5O2
3CO2
4H2O
•What is the mole ratio of propane to oxygen?
1/5
•What is the mole ratio of propane to carbon dioxide?
1/3
•What is the mole ratio of oxygen to water?
5/4
•How many moles of carbon dioxide are made from 2 moles of propane?
Mole Ratios
C3H8
5O2
3CO2
4H2O
•What is the mole ratio of propane to oxygen?
1/5
•What is the mole ratio of propane to carbon dioxide?
1/3
•What is the mole ratio of oxygen to water?
5/4
•How many moles of carbon dioxide are made from 2 moles of propane? 6
Mole Ratios
C3H8
5O2
3CO2
4H2O
•What is the mole ratio of propane to oxygen?
1/5
•What is the mole ratio of propane to carbon dioxide?
1/3
•What is the mole ratio of oxygen to water?
5/4
•How many moles of carbon dioxide are made from 2 moles of propane? 6
•Do you think you could determine how many kg of carbon dioxide are
produced by one kg of propane? Take 2 minutes and write out your method.
Mole Ratios
C3H8
5O2
3CO2
4H2O
•What is the mole ratio of propane to oxygen?
1/5
•What is the mole ratio of propane to carbon dioxide?
1/3
•What is the mole ratio of oxygen to water?
5/4
•How many moles of carbon dioxide are made from 2 moles of propane? 6
•Do you think you could determine how many kg of carbon dioxide are
produced by one kg of propane? Take 2 minutes and write out your method.
Convert 1 kg propane to moles > multiply by mole ratio of 3 to get
moles of carbon dioxide > Convert moles of carbon dioxide to kg.