1. Chapter 11
Stoichiometry

2. Stoichiometry
The study of quantitative relationships between the amounts of reactants used and amounts of products formed by a chemical reaction
Law of Conservation of Mass

3. How Much?
If you were making cookies, you would need the right amount of each ingredient to get the two dozen cookies the recipe makes.
When performing a chemical reaction it is important to know how much of each reactant is needed to get the desired amount of product(s).

4. Balanced Equations
The first step in determining anything in stoichiometry is balancing the chemical equation – Let’s Review!
N H2 → NH3

5. Practice CH4 + O2 → CO2 + H2O NaOH + CaBr2 → Ca(OH)2 + NaBr
H2 + Cl2 → HCl
Li + H2O → LiOH + H2

6. Types of Relationships
Particle to Particle
Mole to Mole
Mass to Mass
C3H8(g) + 5O2(g)→ 3CO2(g)+ 4H2O(g)
44.10 g of propane gas reacts with g of oxygen gas to form g of carbon dioxide gas and g of water vapor.
One molecule of propane gas reacts with five molecules of oxygen gas to form three molecules of carbon dioxide gas and four molecules of water vapor.
One mole of propane gas reacts with five moles of oxygen gas to form three moles of carbon dioxide gas and four moles of water vapor.

7. Practice 5. 2H2O(g) → 2H2(g)+ O2(g)
6. 2NaCl(aq) + MgBr2(aq) → MgCl2(s)+ 2NaBr(aq)
7. CaO(s) + CO2(g) → CaCO3(s)

8. Mole Ratio
The ratio between the numbers of moles of any two substances in a balanced chemical equation. Taken from the coefficients of the balanced equation.
2K(s) + Br2(l) → 2KBr(s)
1 mol Br2 1 mol Br2
2 mol K 2 mol KBr
2 mol K 2 mol K
1 mol Br2 2 mol KBr
2 mol KBr 2 mol KBr
1 mol Br2 2 mol Br2

9. Mole Ratio
For reactions with more reactants and products there are more mole ratios
BaS(aq) + 2KOH(aq) → Ba(OH)2 + K2S
1 mol BaS 1 mol BaS 1 mol BaS
2 mol KOH 1 mol Ba(OH)2 1 mol K2S
2 mol KOH 2 mol KOH 2 mol KOH
1 mol BaS 1 mol Ba(OH)2 1 mol K2S

10. Practice 8. H2 + Cl2 → HCl 9. H2O → H2 + O2 10. C2H10 + O2 → CO2 + H2O
11. LiOH + CaBR → Ca(OH)2 + LiBr

11. Mole to Mole Conversions
N H2 → 2NH3
If we have one mole of nitrogen gas, we need three moles of hydrogen gas in order to produce two moles of ammonia.
What if we have mol of nitrogen gas?

12. Mole to Mole Conversions
N H2 → 2NH3
What if we have mol of nitrogen gas?
Use mole ratios
3 mol H2
1 mol N2
2 mol NH3
0.012 mol N2 ×
= mol H2
0.012 mol N2 ×
= mol H2

13. Practice 12. 0.6 mol hydrogen gas H2 + Cl2 → HCl
mol oxygen gas
C2H10 + O2 → CO2 + H2O
mol hydrogen gas
H2O → H2 + O2
mol lithium hydroxide
LiOH + CaBr2 → Ca(OH)2 + LiBr

14. Mole to Mass Conversions
N2(g) + 3H2(g) → 2NH3(g)
What if we have 5.20 mol of nitrogen gas? How many grams of ammonia are produced in an excess of hydrogen gas?
Use mole ratios, then molar mass
2 mol NH3
1 mol N2 ×
5.20 mol N2
= 15.6 mol NH3
17.03 g
1 mol NH3
15.6 mol NH3 ×
= 266 g NH3

15. Mole to Mass Conversions
4Al(s) + 3O2(g) → 2Al2O3(s)
What if we have 0.42 mol of oxygen gas? How many grams of aluminum oxide are produced in an excess of aluminum solid?
Use mole ratios, then molar mass
2 mol Al2O3
3 mol O2 ×
0.42 mol O2
= 0.28 mol Al2O3 g
1 mol Al2O3
0.28 mol Al2O3 ×
= 29 g Al2O3

16. Practice 16. 0.6 mol chlorine gas Na(s) + Cl2(g) → NaCl(s)
mol oxygen gas
P(s) + O2(g) → P2O5(s)
mol oxygen gas
CH4(g) + O2(g) → CO2(g) + H2O(g)
mol sodium bromide
NaBr(s) + CaF2(s) → CaBr2(s) + NaF(s)

17. Mass to Mass Conversions
N2(g) + 3H2(g) → 2NH3(g)
What if we have 27 g of nitrogen gas? How many grams of ammonia are produced in an excess of hydrogen gas?
Use molar mass, then mole ratios, then molar mass
1 mol N2
28.01 g N2
27 g N2 ×
= 0.96 mol N2
2 mol NH3
1 mol N2
0.96 mol N2 ×
= 1.92 mol NH3
17.03 g
1 mol NH3 ×
1.92 mol NH3
= 33 g NH3

18. Mass to Mass Conversions
4Al(s) + 3O2(g) → 2Al2O3(s)
What if we have 14.3 g of oxygen gas? How many grams of aluminum oxide are produced in an excess of aluminum solid?
Use molar mass, mole ratios, then molar mass
1 mol O2
32.00 g O2 ×
14.3 g O2
= mol O2
2 mol Al2O3
3 mol O2 ×
0.447 mol O2
= mol Al2O3 g
1 mol Al2O3
0.298 mol Al2O3 ×
= 30.4 g Al2O3

19. Practice 20. 46 g chlorine gas Na(s) + Cl2(g) → NaCl(s)
g oxygen gas
P(s) + O2(g) → P2O5(s)
g oxygen gas
CH4(g) + O2(g) → CO2(g) + H2O(g)
g sodium bromide
NaBr(s) + CaF2(s) → CaBr2(s) + NaF(s)