1. Stoichiometry
Stoichiometry (  /ˌstɔɪkiˈɒmɨtri/) is a branch of chemistry that deals with the relative quantities of reactants and products in chemical reactions.
used to find quantities such as the amount of products (in mass, moles, volume, etc.) that can be produced with given reactants and percent yield
founded on the law of conservation of mass: the mass of the reactants equals the mass of the products.
=-from Wikipedia

2. Relationships shown in Chemical Equations
Balanced Chemical Equation
4 Fe (s) O2 (g)  Fe2O3 (s)
Word equation
Iron (III)
Oxygen
Iron (III) Oxide
Particle Model
Atom/Molecule Relationship
4 atoms Fe
3 molecules O2
2 Formula Units Fe2O3
Mole to mole Relationship
4 mol Fe
3 mol O2
2 mol Fe2O3
Mass relationship
223.4 g Fe
96.00 g O2
319.4 g Fe2O3
Reactant-Product Relationship
319.4 g reactants
319.4 g products.

3. Relationships shown in Chemical Equations
Identify ALL of the molar ratios in the equation.
4 P + 5 O2  2 P2O5
What is the molar mass of each substance?

4. Relationships shown in Chemical Equations
6)  Chlorine is used by textile manufacturers to bleach cloth. Excess chlorine is destroyed by its reaction with sodium thiosulfate, Na2S2O3:
Na2S2O3(aq) + 4Cl2(g) + 5H2O(aq)  2NaHSO4(aq) + 8HCl(aq) 
a. How many moles of Na2S2O3 are needed to react with 0.12mol of Cl2?
 b. How many moles of HCl can form from 0.12mol of Cl2?

5. Stoichiometry
Limiting Reactants

6. A cake recipe calls for 2 cups of water 4 cups of flour
8 squares of chocolate
4 cups of sugar
8 oz of butter
4 eggs
According to Model 1, how much of each ingredient is necessary to make a cake?
2 c water
4 cups of flour
8 squares of chocolate
4 cups of sugar
8 oz butter
4 eggs
If you follow the recipe, using only the ingredients on hand in the model, how much of each ingredient will be left over after you have baked the cake?
lots
1 cup
4 squares
none
8 oz.
2 eggs

7. Which of the ingredients on hand were in excess for the recipe?
A cake recipe calls for
2 cups of water
4 cups of flour
8 squares of chocolate
4 cups of sugar
8 oz of butter
4 eggs
Which of the ingredients on hand were in excess for the recipe?
Which of the ingredients on hand were consumed completely in making the cake?
Which of the ingredients limit or prevent you from making a second cake?
What would be a good definition for the term limiting ingredient?
lots
1 cup
4 squares
none
8 oz.
2 eggs

8. Limiting Reactant
You have 10 bolts, 15 nuts, and 15 washers. You assemble a nut/bolt/washer set using the following recipe or equation. 2 washers + 1 bolt + 1 nut = 1 set
How many sets can you assemble from your supply?
Which is the limiting component?
How can you identify the limiting component in some manufacturing process?

9. Limiting Reactant
How could we write a chemical equation for this example?

10. Limiting Reactant
If have 365 cars and 1208 tires, how many cars can I make?

11. Check problem #1
Ammonia (NH3) is one of the most common chemicals produced in the United States. It is used to make fertilizer and other products. Ammonia is produced by the following chemical reaction.
N2(g)  3H2(g)  2NH3(g)
a. If you have 1.00 x 103 g of N2 and 2.50 x 103 g of H2, which is the limiting reactant in the reaction?
b. How many grams of ammonia can be produced from the amount of limiting reactant available?
c. Calculate the mass of excess reactant that remains after the reaction is complete.