Limiting Sims 1
Name
Date
Period
Limiting and Excess Reactants Simulations
Purpose
After reading the lab, create your own purpose below:
Pre-Lab Discussion
In most chemical reactions that have multiple reactants, one of the reactants will be used up
before the other reactants. This substance is known as the limiting reactant. The limiting reactant
will determine the maximum amount of product that can be made with the quantities available.
All of the other substances are known as the excess reactants and have some remaining quantity
after the reaction. Knowing the limiting reactant and its starting amount, you can determine the
yield of product and the amount of excess reactant remaining after the reaction.
Procedure
Part 1 - The Sandwich Shop
1. If you have 6 pieces of bread and 4 slices of cheese, predict how many cheese
sandwiches of type “a” you can make. Then predict how many of type “b” you can make.
a:
b:
2. How did you figure this out?
3. To access the simulation either click on the link:
http://phet.colorado.edu/en/simulation/reactants-products-and-leftovers
OR Google: Phet Colorado Limiting Simulation
4. Check your predictions using the “Sandwich Shop” tab. Do the results make sense?
Revise your answers or reasoning as needed.
5. In case A, the bread could be called the “limiting reactant.” How would you define a
“limiting reactant”?
Limiting Sims 2
6. What is the limiting reactant for case B and why? What is leftover when all the
sandwiches are made?
Part 2 – Making Ammonia
7. Consider the chemical equation:
1 N2 + 3 H2 → 2 NH3
8. For the 3 scenarios below, predict which one will produce the most ammonia, and predict
which ones will have leftovers.
a:
b:
c:
9. Explain your reasoning:
10. Click on the “Real Reaction” tab at the top of the simulation. Select “Make ammonia
from the options on the left.
11. Now check your predictions with the simulation. Do the results make sense? Revise your
answers or reasoning as needed.
12. How did the “Real Reaction” tab relate to the “Sandwich Shop” tab?
Limiting Sims 3
Part 3 – The Game
13. Click on the “Game!” tab at the top of the simulation. Turn off the sound. Try to
complete the game in the fastest possible time. Record your best score and time for each
level in the table below.
Level
Best Score
Time
1
2
3
14. How did you solve the problems? Write your strategy in the space below. Did your
strategy change as you played the game? If so, write how it changed.
Question
1. When solid, metallic aluminum Al and red, liquid bromine Br2 are brought together, they
make a white solid according to the reaction:
2Al + 3 Br2 → 2 AlBr3
If 3.45 grams of Al and 4.79 grams of Br2 react:
a. How much AlBr3 gets produced? (Show your work!)
b. Which chemical is the limiting reactant?
c. Which chemical must be the excess reactant?
d. If all the limiting reactant gets used up, how much of the excess reactant is
left?