1. Bell Ringer
Aqueous hydrochloric acid reacts with solid potassium chlorate to produce gaseous chlorine, aqueous potassium chloride and liquid water.
Write a balanced chemical equation for the above reaction.
If 0.40 mols of hydrochloric acid are placed in a beaker, how many mols of solid potassium chlorate will be needed to react with all the hydrochloric acid?
If the 0.40 mols of hydrochloric acid react completely, how many mols of chlorine gas will be produced?

2. Limiting and Excess Reagents
Unit 8 Stoichiometry:
Limiting and Excess Reagents

3. Limiting reagents
Suppose you have 25 slices of turkey (T) and 36 slices of bread (B).
How many sandwiches can you assemble according to the “eqn” below
2B + T  B2T
How come you can’t make 25 sandwiches?
All of the bread slices are used (limiting)
What’s left over (excess)

4. Limiting Reactant
Given 4 molecules of hydrogen gas and 4 molecules of oxygen gas to form water. Write the balanced equation for the reaction between hydrogen and oxygen.
Balanced Equation:
Make a drawing that represents the reaction container before and after the reaction.
4 molecules of water are formed
2 molecules of oxygen are “left over” (in excess). HC?

5. Limiting Reactant Let’s look at a BCA table: What are the mole ratios?
4 molecules of water are formed
2 molecules of oxygen are “left over” (in excess). HC?

6. Example
Find the mass of CO2 formed when 100 g of methane, CH4, combines with 150 g of oxygen to produce CO2 and H2O. B C A
Which one is limiting?
Present
Need

7. Example
Find the mass of CO2 formed when 100 g of methane, CH4, combines with 150 g of oxygen. B C A
Mole calculations and ratios use the limiting reactant, O2:

8. Percent yield
Suppose in the last example we only had a 90.2 g yield, what’s the % yield?
TY= 103 g
AY= 90.2 g
%yld= ?

9. Assignment
Unit 8 WS #3