Irrelevant Information to Take Your Mind Off of Stoichiometry
The first person to use the word “stoichiometry” was Nicephorus I, the ecumenical Patriarch of Constantinople in the early 9th century.
However, the term as he used it refers to the number of lines of text in the New Testament. This suggests that the term “stoichiometry” has been annoying people for over a millennium.
Image: Classical Numismatic

Chapter 11: Stoichiometry
• Be able to complete molarity equations/problems
• Know mole ratio’s
• Use mole ratio’s to complete stoichiometry problems
• Complete:
• Mol/mol
• mol/mass
• Mass/mass
• Identify limiting and excess reactants
• Calculate the % yield

Molarity:
• describes how much solute there is per solution.
Molarity (M) = Moles of solute
Liters of solution
*aqueous solutions are solutes dissolved in water.

Molarity:
• We have a solution that is made of 45.6 grams of sodium chloride dissolved in 378 mL of water. What is the solutions molarity? (Answer=2.08 M)
Step 1: Change grams to moles
45.6g NaCl 1 mol NaCl
58g NaCl
Step 2: Change volume to liters
= 0.786 mol NaCl
378 mL 1 L
1000 mL
= 0.378 L
Step 3: Divide the number of moles by the volume of the solution
0.786 mols NaCl
= 2.08 M
0.378 L

Molarity Practice: Write these down in your notes
• A solution is made by dissolving 3.21 moles of sulfuric acid into 506 mL of water. What is the molarity of the solution?
• If a solution is made by adding 3230 grams of lithium carbonate to 2.2 liters of water, what will the molarity of the solution be?
• 121.4 grams of potassium oxide are dissolved in 34.5 mL of water, what is the solutions molarity?

Molarity Practice Problem #1:
• A solution is made by dissolving 3.21 moles of sulfuric acid into 506 mL of water. What is the molarity of the solution?

Molarity Practice Problem #2:
• If a solution is made by adding 3230 grams of lithium carbonate to 2.2 liters of water, what will the molarity of the solution be?

Molarity Practice Problem #3:
• 121.4 grams of potassium oxide are dissolved in 34.5 mL of water, what is the solutions molarity?

Stoichiometry:
• The quantitative relationships between the amounts of reactants used and the amounts of products formed by a chemical reaction.
• Which is just a fancy way of saying:
• “the method you use to figure out how much of a chemical you can make, or how much you need, during a reaction.”
• What is Stoichiometry?

Stoichiometry:
• 1. How to balance chemical equations
• 2. How to convert grams to moles/moles to grams
• 3. How to use mole ratios
Can you do 1 and 2?

Mole Ratios:
• Ratio - a relationship between two numbers of the same kind.
2H
2
+ O
2
2H
2
O
*Use the coefficients of the balanced chemical reaction to determine the mole ratios.
Ratios:
2 hydrogen for 1 oxygen
2 hydrogen for 2 water
1 oxygen for 2 water

Mole Ratio’s:
Calculate the mole ratio for each substance in the following reactions.
__Fe + __O
2
⇒ __Fe
2
O
3
__C
3
H
8
+ __O
2
⇒ __CO
2
+ __H
2
O

Stoichiometry and Mole Ratios:
• Knowing the mole ratios allows you to begin doing stoichiometry:
2 H
2
+ O
2
2 H
2
O
If we have 5 moles of hydrogen reacting, how many moles of water are formed?
The
Amount
Given
5 moles H
2
2 moles H
2
O
= 5 moles H
2
O
2 moles H
2
Mole ratio between the two compounds in the problem

Stoichiometry: mols to mols
If there are 3.5 moles of potassium reacting, how many moles of hydrogen will form?

Mols to Mols Practice:
Complete in your notes
__Fe + __O
2
⇒ __Fe
2
O
3
If you only had 0.45 moles of Fe how many moles of Fe2O3 would you produce?
How many moles of O2 were used?

Mols to Mols Practice:
Complete in your notes
__C
3
H
8
+ __O
2
⇒ __CO
2
+ __H
2
O
If 7.8 moles of O
2 are used how much C
3
H
8 was also used?
How many moles of CO
2 were produced?

Mols to Mols Practice:
Complete in your notes
__AgNO
3
+ __Cu ⇒ __Cu(NO
3
)
2
+ __Ag
10.2 moles Cu are used to react with AgNO
3
, how many moles of
AgNO
3 were used to react?
How many moles of Silver are produced?