1. Chemistry 12.1 Stoichiometry
“The arithmetic of equations”

2. Chapter 12 Objective
This unit will allow you to calculate the amounts of chemical substances involved in a chemical reaction.
 You will use balanced chemical equations to do this…

3. Tiny Tricycles – 12.1 wks… Cookie Example

4. B. Cookie Example 1. Recipe… 2. You have…
2 large eggs + 1/2 cup sugar + 1 teaspoon vanilla + 3 tbsp cocoa powder + 1/2 cup chocolate chips
 chocolate chip cookies
16 large eggs
12 cups sugar
6 teaspoons vanilla
33 tbsp cocoa powder
18 cups chocolate chips
 ? chocolate chip cookies
48 chocolate chip cookies

5. 4. What do you need for 4 dozen cookies?
3. What do you have left?
4. What do you need for 4 dozen cookies?
4 eggs
9 cups of sugar
15 tbsp of cocoa powder
15 cups of chocolate chips
12 eggs
3 cups of sugar
6 teaspoons of vanilla
18 tbsp of cocoa powder
3 cups of chocolate chips

6. Write you own example equation about and item that has multiple parts/pieces…

7. I. Stoichiometry
A. Def - a calculation of chemical quantities in a chemical reaction.
1. Our formula
1 N2 (g) + 3 H2 (g)  2 NH3 (g)
2. What can we determine with a balanced chemical equation???
a. 1 : 3 : 2 ratio
-this applies to atoms, molecules, or moles; mass; and volume.

8. 1 N2 (g) + 3 H2 (g)  2 NH3 (g) Particles… Moles… Grams… 2 atoms of N
6 atoms of H
2 atoms N
+ 6 atoms H
Particles are conserved…
1 mol N2
mol H2
 mol NH3
Moles don’t have to be conserved…
28 g of N2
+ 6 g of H2
 34 g of NH3
Mass is conserved…

9. *Mass and atoms are always conserved…
Gas/Volume (at STP)…
*Mass and atoms are always conserved…
*Molecules, formula units, moles, and volumes are not necessarily conserved
22.4 L of N2
L of H2
 L of NH3
Volume doesn’t have to be conserved…

10. 2 H2S(g) + 3 O2(g)  2 SO2(g) + 2 H2O(g)
Hydrogen sulfide, a foul smelling gas, is found in nature in volcanic areas. The balanced chemical equation for the burning of hydrogen sulfide is given above. Interpret this equation in terms of the interaction of the three relative quantities. Do to this equation as what was on the last screen.
a. Number of particles
b. Number of moles
c. Masses of reactants and products

11. a. Particles b. Moles c. Grams 2 molecules H2S + 3 molecules O2
 2 molecules SO2
+ 2 molecules H2O
2 mol H2S
+ 3 mol O2
 2 mol SO2
+ 2 mol H2O
68.2 g H2S
g O2
 g SO2
g H2O
164.2 g reactants = g products

12. In Class Assignment C2H2 (g) + O2 (g)  CO2 (g) + H2O (g) a. Balance
b. Number of particles
c. Number of moles
d. Masses of reactants and products