1. 9.1/9.2 Stoichiometric Calculations
Ch. 9 Stoichiometry
9.1/9.2 Stoichiometric Calculations

2. Stoichiometry
Deals with mass relationships between reactants and products in a chemical reaction
Can be a conversion between two reactants, reactants and products or two products
Review Conversion Basics:
Should you write numbers or units first?
What do you use to convert between g and moles of a compound?
In this conversion, what number goes next to mol?

3. Moles A ⇄ Moles B
to get mole ratios, you must have a balanced chemical equation
tells us the relative amounts of each type of reactant needed to produce each product
used to convert between moles of one substance to moles of another substance

4. Example Al2O3(l)  Al(s) + O2(g)
If the reaction begins with 13.0 mol of Al2O3, how many moles of Al will be created?

5. Example
If we want the reaction to produce 28.0 moles of O2, how many moles of Al2O3 should you begin the reaction with?
How many moles of Al will you also end with?

6. Grams ⇄ Moles use molar mass and mole ratio Grams A  Moles B
grams A  moles A using molar mass
moles A  moles B using mole ratio
Moles A  Grams B
moles B  grams B using molar mass

7. Example 2
If you began the reaction with 2.00 g of Al2O3, how many moles of O2 will you end up with?
g  mol using molar mass
mol  mol using mole ratio

8. Example 2
If the reaction produces 23.7 mol Al, how many grams of O2 should it also end with?
mol  mol
mol  grams

9. Grams A ⇄ Grams B use molar mass twice
grams A moles A using molar mass
moles A  moles B using mole ratio
moles B  grams B using molar mass

10. Example 3
If you begin the reaction with g Al2O3, how many grams of Al would it end with?
grams Al2O3  mol Al2O3 using molar mass
mol Al2O3  mol Al using mole ratio
mol Al  grams Al using molar mass

11. Example 3
If the mass of O2 ended up being 21.9 g, how many grams of Al2O3 did the reaction begin with?
grams O2  mol O2 using molar mass
mol O2  mol Al2O3 using mole ratio
mol Al2O3  grams Al2O3 using molar mass