1. Stoichiometry

2. Stoichiometry Basics
Stoichiometry is the study of the quantitative relationships that exist in chemical formulas and balanced chemical equations.
Stoichiometry allows us to calculate the amounts of substances that are related by a balanced chemical equation.

3. Do You Remember? 4 Fe + 3 O2 → 2 Fe2O3 8 Fe + 6 O2 → 4 Fe2O3
4 mol Fe mol O2 → 2 mol Fe2O3
0.24 mol Fe mol O2 → 0.12 mol Fe2O3

4. Interpreting Balanced Equations
Balance the equation...
Cu + AgNO3 → Cu(NO3) Ag 2
This means that 1 mole of copper reacts with 2 moles of silver nitrate to form 1 mole of copper (II) nitrate and 2 moles of silver.

5. Balance the equation... Mole - Mole Problems Li + N2 → Li3N 2 6 2 6
How many moles of Li3N can be produced if 3.00 moles of lithium reacts completely with nitrogen?

6. How many moles of N2 are required to react with 7.2 moles of Lithium?
Review Example
Li + N2 → Li3N 2 6
How many moles of N2 are required to react with 7.2 moles of Lithium?

7. 2 H3PO4 + 3 Mg(OH)2 → Mg3(PO4)2 + 6 H2O
Mass
Volume
Moles in
moles moles moles moles moles moles moles moles moles moles moles moles moles mole
moles
2 H3PO4 + 3 Mg(OH)2 → Mg3(PO4)2 + 6 H2O
The balanced chemical equation is the gateway.
Moles out
Mass
Volume

8. The balanced chemical equation is the gateway.
2 H3PO4 + 3 Mg(OH)2 → Mg3(PO4)2 + 6 H2O
Moles in
Mass
Volume
Moles out
moles moles moles moles moles moles moles moles moles moles moles moles moles mole
moles
Molar mass or
Formula mass
Molar volume
Molar mass or
Formula mass
Molar volume

9. Mass - Mass Conversions
How many grams of SnF4 can be formed from 12.8 g of HF?
Sn + 4HF → SnF H2
20.01 g HF
1 mol Hf

10. Mass - Volume Problems 2 Mg + O2 → 2 MgO
How many liters of O2(g) are needed at STP to burn 60.0 g of magnesium?
2 Mg O2 → 2 MgO

11. Volume - Volume Problems
How many liters of H2O(g) can be formed from 48.9 L of CH4(g) at STP?
CH O2 → CO H2O
Notice that numerically the first ratio and the third ratio cancel out. For vol/vol problems the mole ratio is sufficient.

12. Maximum labeling -
C6H12O6 → 2 C2H6O + 2 CO2

13. (and,… just what is a limiting reactant?)
Limiting Reactants
Under what conditions do we need to be concerned about limiting reactants?
(and,… just what is a limiting reactant?)

14. What mass of iron (IV) sulfide is formed when 20
What mass of iron (IV) sulfide is formed when 20.0 g of iron reacts with sulfur?
4 Fe + S8 → 4 FeS2

15. What mass of iron (IV) sulfide is formed when 20
What mass of iron (IV) sulfide is formed when 20.0 g of sulfur reacts with iron?
4 Fe + S8 → 4 FeS2

16. Summary
4 Fe + S8 → 4 FeS2

17. What happens at this point?
4 Fe + S8 → 4 FeS2
The reaction STOPS!

18. Since there is some iron left over we say it is in excess.
Since sulfur causes the reaction to stop we call sulfur the limiting reactant in this reaction.
Since there is some iron left over we say it is in excess.

19. 2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O
What is the limiting reactant in the following reaction?
2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O

20. 2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O
What is the limiting reactant in the following reaction?
2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O

21. 2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O
What is the limiting reactant in the following reaction?
2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O

22. 2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O
What is the limiting reactant in the following reaction?
2Al(OH)3 + 3H2CO3 → Al2(CO3)3 + 6H2O