1. Chapter 12 Stoichiometry
The study of the quantitative relationship between the amounts of reactants and products in a chemical reaction.

2. Goals Perform stoichiometry calculations.
Understand limiting reactants.
Calculate the theoretical and percent yields of a chemical reaction.

3. What is stochiometry? “stochio” = Greek for element
“metry” = measurement
Stoichiometry is about measuring the amounts of elements and compounds involved in a reaction.

4. Why is it important to be able to calculate the amount of substances involved in chemical reactions?
Demo:
Cu + AgNO3 
Type of reaction?
What would my products be?

5. What data might we need to collect?

6. Day 1: Initial mass of Copper  Mass of beaker  Volume of Silver Nitrate  Day 2: Final mass of Copper Theoretical Yield Silver *Do a stoichiometry mass to mass problem to determine how many grams of Silver Day 3: Mass of Beaker and Silver Mass of Silver 

7. Solving Stoichiometry Problems
Need the balanced chemical reaction.
Coefficients in a balanced equation can represent
# of moles of each substance
# of molecules of each substance
# of atoms
g of each substance
22.4 L for each mole of gas STP
Remember mass and atoms are conserved in a chemical reaction!

8. 3H2 + N2  2 NH3 6 atoms H + 2 atoms N  2 atoms N & 6 atoms H 6
3H2 + N2  2 NH3 6 atoms H + 2 atoms N  2 atoms N & 6 atoms H 6.06 g H g N  g of product 3 molecules H2 + 1 molecule N2  2 molecules ammonia 3 moles H2 + 1 mole N2  2 moles ammonia 67.2 L H L N2  44.8 L NH3

9. Video
physics/chemistry/801

10. You will be using the mole relationships from the balanced equation for the calculations in this chapter.
H2 + I2  2 HI
2H2S O2  2SO H2O

11. How many moles of aluminum are needed to form 3
How many moles of aluminum are needed to form 3.7 moles of aluminum oxide? How many moles of oxygen are required to react completely with 14.8 moles of Aluminum?

12. Calculate the number of moles of aluminum oxide formed when 0
Calculate the number of moles of aluminum oxide formed when moles of oxygen react with aluminum.

13. How many moles of carbon dioxide are produced when 3
How many moles of carbon dioxide are produced when 3.67 moles of Ethyne, C2H2 reacts with oxygen? How many moles of oxygen need to react with ethyne to produce 6.92 moles of water?

14. Day 1: Initial mass of Copper  0. 72g Mass of beaker  49
Day 1: Initial mass of Copper  0.72g Mass of beaker  49.48g Volume of Silver Nitrate 38.8 mL Day 2: Final mass of Copper 0.58g 0.72g g = 0.14g of Copper used Day 3: Mass of Beaker and Silver 49.93g Mass of Silver  = 0.45g Silver Theoretical Yield Silver *Do a stoichiometry mass to mass problem to determine the theoretical mass of Silver

15. Moving along the stoichiometry path
We always use the same type of information to make the jumps between steps:
grams (x)  moles (x)  moles (y)  grams (y)
Molar mass of y
Molar mass of x
Mole ratio from balanced equation