Put on Pg 49 of your notebook

1
Put on Pg 49 of your notebook!

• 79.1 g of Zn react with 50.0 L of HCl
• How many liters of H2 are formed at STP using the
  amount of Zn?
• How many liters of H2 are formed at STP using the
  amount of HCl?

Zn 2HCl ? ZnCl2 H2
2
Follow along in your textChapter 9 Section 2
Pages 312 319

• Stoichiometric Applications

3
Limiting Reactants

• Available Ingredients
• 4 slices of bread
• 1 jar of peanut butter
• 1/2 jar of jelly

• Limiting Reactant
• bread

• Excess Reactants
• peanut butter and jelly

4
Limiting Reactants

• Limiting Reactant
• used up in a reaction
• determines, or limits, the amount of product
• Excess Reactant
• added to ensure that the other reactant is
  completely used up
• usually cheaper easier to recycle

5
Limiting Reactants

• 1. Write a balanced equation.
• 2. For each reactant, calculate the amount of
  product formed.
• 3. Smallest answer indicates
• limiting reactant
• amount of product

6
Limiting Reactants

• 79.1 g of zinc react with 50.0 L of HCl.
  Identify the limiting and excess reactants. How
  many liters of hydrogen are formed at STP?

Zn 2HCl ? ZnCl2 H2
? L
79.1 g
50.0 L
7
Limiting Reactants
Zn 2HCl ? ZnCl2 H2
? L
79.1 g
50.0 L
79.1 g Zn
1 mol Zn 65.39 g Zn
1 mol H2 1 mol Zn
22.4 L H2 1 mol H2
27.1 L H2
8
Limiting Reactants
Zn 2HCl ? ZnCl2 H2
? L
79.1 g
50.0 L
22.4 L H2 1 mol H2
50.0 L
1 mol HCl 22.4 L HCl
1 mol H2 2 mol HCl
25 L H2
9
Limiting Reactants

• Zn 27.1 L H2 HCl 25 L H2

Limiting reactant HCl Excess reactant
Zn Product Formed 25 L H2
10
Percent Yield
11
Percent Yield

• When 45.8 g of K2CO3 react with excess HCl, 46.3
  g of KCl are formed. Calculate the theoretical
  and yields of KCl.

K2CO3 2HCl ? 2KCl H2O CO2
45.8 g
? g
actual 46.3 g
12
Percent Yield
K2CO3 2HCl ? 2KCl H2O CO2
45.8 g
? g
actual 46.3 g

• Theoretical Yield

45.8 g K2CO3
1 mol K2CO3 138.21 g K2CO3
2 mol KCl 1 mol K2CO3
74.55 g KCl 1 mol KCl
49.4 g KCl
13
Percent Yield
K2CO3 2HCl ? 2KCl H2O CO2
45.8 g
49.4 g
actual 46.3 g

• Theoretical Yield 49.4 g KCl

? 100
93.7
Yield