Name _______________________________ Teacher _________________ Date __________
Lesson 5.1 Grading Explaining Burning
Methane Worksheet
Use this worksheet to grade student responses. At this point, students can be held
accountable for correct answers. If students are still struggling with these concepts,
you may want to revisit parts of the Lesson they are finding difficult. General
characteristics of correct responses are in bold blue italics.
Now let’s explain what happens when another fuel burns: Methane (natural gas). Try
answering the Three Questions for what happens when a gas stove burns methane
(CH4). Methane burns in the same way as ethanol burns: molecules of methane
combine with oxygen to produce carbon dioxide and water. To explain what happens
when methane burns, you need to answer the Three Questions:
1. The Movement Question: Where are atoms moving?
2. The Carbon Question: What is happening to carbon atoms?
3. The Energy Question: What is happening to chemical energy?
A. Answering the Movement Question. Show how atoms are moving in the gas
flame.
What kinds of molecules are coming into
Drawing motions of atoms: Draw arrows
the bottom of the flame?
to show how atoms move into, through,
and out of the flame.
Methane, oxygen, (nitrogen). Nitrogen
and other gases are present but are not
There should be arrows showing:
involved in the chemical change.
• Methane entering the flame from
What kinds of molecules are leaving the
the bottom.
top of the flame?
• Oxygen entering the flame at the
Carbon dioxide, water, (nitrogen,
bottom (Stovetop burners actually mix
oxygen). Not all oxygen molecules are
the methane with air before it comes
involved in the chemical reaction.
out of the burner, but students will not
know this, so arrows showing the
oxygen coming from the air are fine.)
• Carbon dioxide and water leaving
the flame at the top.
Photo Credit: Craig Douglas, Michigan State University
Systems and Scale Unit, Lesson 5, Activity 1
Environmental Literacy Project
Michigan State University
B. (Optional) Using molecular models to show the chemical change. Use molecular
models to show what happens when methane burns:
1. Work with your partner to make models of the reactant molecules: methane (CH4)
and oxygen (O2, with a double bond). Put a twist tie around each high-energy bond
(C-C and C-H bonds) in the methane molecule. Put these molecules on the reactant
side of the Process Tool for Molecular Models 11 x 17 Poster.
2. Show how the atoms of the reactant molecules can recombine into product
molecules—carbon dioxide and water—and show how chemical energy is released
when this happens. Take the ethanol and the oxygen molecules apart and
recombine them into carbon dioxide (CO2) and water (H2O) molecules. Put these
molecules on the product side of the Process Tool for Molecular Models 11 x 17
Poster. Notice how many of each type of molecule you have. Carbon dioxide and
water have only low-energy bonds (C-O and H-O), so what forms of energy does
the chemical energy change into?
C. Atoms last forever! Check yourself: did your number and type of atoms stay the
same at the beginning and end of the chemical change? Use the table below to
account for all the atoms and bonds in your models.
Energy lasts forever! Write the type of energy for reactants and products in the
chemical change.
Matter
Reactants
Methane
Oxygen
Reactants
totals
Products
Carbon
Dioxide
Water
Products
totals
Energy
How
many
carbon
atoms?
How many
oxygen
atoms?
How many
hydrogen
atoms?
How many
twisty ties?
1
0
4
4
0
4
0
0
1
4
4
4
1
2
0
0
2
4
1
4
4
4
What forms of
energy?
Chemical
Heat, light
Systems and Scale Unit, Lesson 5, Activity 1
Environmental Literacy Project
Michigan State University
2
D. Writing the chemical equation. Use the molecular formulas (CH4, O2, CO2, H2O)
and the yield sign (à) to write a balanced chemical equation for the reaction:
CH4 + 2O2 à CO2 + 2 H2O
E. Using the Process Tool to answer the Three Questions. Answer the Three
Questions using the Process Tool below.
Gas pipe, air
Methane or CH4
Oxygen or O2
Chemical energy
(energy in C-C and C-H bonds)
Air (at top of flame)
Carbon dioxide or CO2
Water or H2O
Heat, light, (motion)
Systems and Scale Unit, Lesson 5, Activity 1
Environmental Literacy Project
Michigan State University
3