1. 7.4 Calculations Involving Limiting Reagents

2. Double Cheeseburgers and Stoichiometry
1 Double Cheeseburger needs 1 bun, 2 patties, 2 slices of cheese, 4 strips of bacon
For 5 Double Cheeseburgers how many units of each ingredient do I need?
Fill in the final column below with how many complete burgers I can make:
Buns
Patties
Cheese Slices
Bacon Strips
How Many Burgers? 2 4 8 16 30 32 48

3. Objectives To understand the concept of limiting reactants
To learn to recognize the limiting reactant in a reaction
To learn to use the limiting reactant to do stoichiometric calculations

4. A. The Concept of Limiting Reactants
Stoichiometric mixture
N2(g) + 3H2(g)  2NH3(g)

5. A. The Concept of Limiting Reactants
Limiting reactant mixture
N2(g) + 3H2(g)  2NH3(g)

6. A. The Concept of Limiting Reactants
For a Limiting reactant mixture the number of moles are not balanced to match the reaction equation
N2(g) + 3H2(g)  2NH3(g)
Limiting reactant is the reactant that runs out first
When the limiting reactant is exhausted, then the reaction stops

7. B. Calculations Involving a Limiting Reactant

8. B. Calculations Involving a Limiting Reactant
The are two ways which we can solve for limiting reagents.
Way 1: Uses the mole ratio as a comparison of have and need
Way 2: Has two final answers and we always select the lowest.

9. B. Calculations Involving a Limiting Reactant Way 1
Run both calculations to the mass and take the answer with the lowest amount of grams

10. Sodium metal reacts with oxygen to produce sodium oxide. If 5
Sodium metal reacts with oxygen to produce sodium oxide. If 5.00 g of sodium reacted with 5.00 grams of oxygen, how many grams of product is formed?
Way 1

11. Sodium metal reacts with oxygen to produce sodium oxide. If 5
Sodium metal reacts with oxygen to produce sodium oxide. If 5.00 g of sodium reacted with 5.00 grams of oxygen, how many grams of product is formed?
Way 2

12. Notice you can not have two different masses produced for the same product in one reaction vessel! So in this case, Na (sodium) “limits” how much sodium oxide is produced. The correct answer is 6.74 g of sodium oxide.

13. b) How much oxygen was used in this reaction and how much of each reactant was leftover (in excess)?
There are two methods used to answer this question. Stoichiometry and the Law of Conservation of mass.

14. How many grams of solid are formed when 10. 0 g of lead reacts with 10
How many grams of solid are formed when 10.0 g of lead reacts with 10.0 g of phosphoric acid?

15. 1. How much AgCl product will be produced if 100
1. How much AgCl product will be produced if g of BaCl2 reacted with excess AgNO3?
2. How many moles of carbon dioxide could be produced from g of C2H2 and g of O2?
3. How many grams of CO2 can be produced by the reaction of 35.5 grams of C2H2 and 45.9 grams of O2?
4. In the reaction between CH4 and O2, if 25.0 g of CO2 are produced, what is the minimum amount of each reactant needed?
5. Cu AgNO3  Cu(NO3) Ag.
When 10.0 g of copper was reacted with 60.0 g of silver nitrate solution, 30.0 g of silver was obtained. What is the percent yield of silver obtained?