Learning Exercise

Chemical Reactions- Building Reactants and Products

Students will use Gum Drops (atoms) and toothpick (chemical bonds) to carry out a chemical reaction.
Course: 8th Grade Physical Science
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Exercise

Chemical Reaction:
Building Reactants and Products

CO2 + 2H2O ‡ CH4 + 2O2
In the above reaction, Carbon Dioxide (CO2) and Water (H2O) react to form
Methane (CH4) and Oxygen (O2).

COLOR KEY:
Carbon (C) Yellow
Hydrogen (H) Blue or Green
Oxygen (O) Red or Orange

1. List the reactants. _____________ _____________
2. List the products _____________ _____________
3. You need to get as many gum drops as there are atoms. Look at the color key
to see what color represents which atom.
a. How many Carbon atoms do you need to start the reaction? _____
b. How many Oxygen atoms do you need to start the reaction? _____
c. How many Hydrogen atoms do you need to start the reaction? ____
4. Now you ca n build your reactants. Remember in order to hold the molecules
together you need chemical bonds (toothpicks).
a. Draw the reactants you have built. Be sure to label the atoms and bonds.








5. It is time to build your products. In order to do this, you will need to
rearrange your reactants. (NOTE: YOU ARE NOT ALLOWED TO USE MORE GUM DROPS!)
a. Draw the products you have built. Be sure to label the atoms and bonds.








6. You have now completed a chemical reaction !!!
a. How many Carbon atoms did you end with? _____
b. How many Oxygen atoms did you end with? _____
c. How many Hydrogen atoms did you end with? _____










Audience

Technical Notes

materials needed:
gumdrops and toothpicks
colored pencils helpful (students draw
what they build)

Requirements

Need to be familiar with the following:
Atom, element, molecule, chemical bond, chemical change

Topics

Reactants, Products, Law of conservation of mass.

Type of Task

Learning Objectives

1. The student should be able to identify the reactants for a given chemical reaction.
2. The student should be able to identify the products for a given chemical reaction.
3. The student should be able to determine the number of reactant atoms needed to initiate the reaction.
4. The student should be able to determine the number of product atoms produced by the reaction.
5. The student should be able to build the reactants with gum drops and toothpicks.
6. The student should be able to build he products with the same amount of gum drops as the reactants.