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Carbon TIMEModeling & Explaining Ethanol Burning
Entry Task:
What are the 2 Energy Facts?
Evidence Based Argument ToolShare with a neighbor,
compare the evidence you selected to help you answer each question.
How are your ideas alike?How are your ideas different?
Compare your claimsHow are they alike and different?
About Evidence
Mass provides good evidence to answer the Movement question
BTB evidence provides only a partial answer to the Carbon question.
• We know Carbon ends up in CO2 detected by the BTB• We DON’T know where the carbon came from in the ethanol
The observation of heat and light in the flame also provide only a partial answer to the Energy question
• We know that energy is released• We DON’T know where the energy came from
Making the Reactant Molecules: Ethanol and Oxygen
The flame of burning ethanol comes when ethanol (C2H5OH) reacts with oxygen (O2).
1. Make a molecules of ethanol and oxygen on the reactant side of your Molecular Models Placemat.
2. Use twist ties to represent energy. 3. Use the Forms of Energy cards to show which form of
energy the twist ties represent. Follow along with your worksheet… • Read Part A• Complete steps B.1a-d
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Oxygen
Carbon Dioxide
Water
Ethanol
What’s the hidden chemical change
when ethanol burns?
?
The bottom of flame at atomic-molecular scale
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The top of flame at atomic-molecular scale
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How Atoms Bond Together in Molecules
• Atoms in stable molecules always have a certain number of bonds to other atoms:• Carbon – • Oxygen – • Hydrogen –
• Oxygen atoms do NOT bond to other oxygen atoms if they can bond to carbon or hydrogen instead.
• Chemical energy is stored in bonds between atoms
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Photo of reactant molecules: C2H5OH (ethanol) and O2 (oxygen)Start by making the molecules and energy units of the reactants and putting them on the reactants side, then rearrange the atoms and energy units to show the products.
Remember: Atoms last forever (so you can rearrange atoms into new molecules, but can’t add or subtract atoms). Energy lasts forever (so you can change forms of energy, but energy units can’t appear or go away)
Reactants Products
Chemical change
Ethanol
Oxygen
Important:
When you are finished constructing the reactants, put all extra pieces away.
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Rearranging the Atoms to Make Product Molecules: Carbon Dioxide and Water
The flame of burning ethanol comes when ethanol (C2H5OH) reacts with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O). Show how this can happen:
Follow along on your worksheet…
Complete steps B.2.a-c
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Photo of product molecules: CO2 (carbon dioxide) and H2O (water)Start by making the molecules and energy units of the reactants and putting them on the reactants side, then rearrange the atoms and energy units to show the products.
Remember: Atoms last forever (so you can rearrange atoms into new molecules, but can’t add or subtract atoms). Energy lasts forever (so you can change forms of energy, but energy units can’t appear or go away)
Reactants Products
Chemical change
Water
Carbon dioxide
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Comparing photos of reactant and product moleculesStart by making the molecules and energy units of the reactants and putting them on the reactants side, then rearrange the atoms and energy units to show the products.
Remember: Atoms last forever (so you can rearrange atoms into new molecules, but can’t add or subtract atoms). Energy lasts forever (so you can change forms of energy, but energy units can’t appear or go away)
Reactants Products
Chemical change
Ethanol
Oxygen
Water
Carbon dioxide
Reactants
Products
Chemical change
What happens to atoms and energy when ethanol burns?
Ethanol
Oxygen
Water
Heat and light energy
Carbon Dioxide
Reactants
Products
Chemical change
Ethanol
Oxygen
Water
Heat and light energy
Carbon Dioxide
What happens to carbon atoms
when ethanol burns?
Carbon atoms in ethanol become part of carbon
dioxide molecules.
Reactants
Products
Chemical change
Ethanol
Oxygen
Water
Heat and light energy
Carbon Dioxide
What happens to oxygen atoms
when ethanol burns?
Oxygen atoms become part of
carbon dioxide and water molecules.
Reactants
Products
Chemical change
Ethanol
Oxygen
Water
Heat and light energy
Carbon Dioxide
What happens to hydrogen atoms
when ethanol burns?
Hydrogen atoms become part of
water molecules.
Reactants
Products
Chemical change
Ethanol
Oxygen
Water
Heat and light energy
Carbon Dioxide
What happens to chemical energy
when ethanol burns?
Chemical energy is transformed into heat
and light energy.
Reactants
Products
Chemical change
What happens to atoms and energy when ethanol burns?
Ethanol
Oxygen
Water
Heat and light energy
Carbon Dioxide
Atoms last forever! Energy lasts
forever!
Writing a Chemical Equation
• Chemists use chemical equations to show how atoms of reactant molecules are rearranged to make product molecules.
• Writing the equation in symbols. Chemists use an arrow to show how reactants change into products.
• Equations must be balanced. Remember: Atoms last forever.
• Try it: Can you write a balanced chemical equation to show the chemical change when ethanol burns?
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Chemical equation for ethanol burning
C2H5OH + 3O2 2 CO2 + 3 H2O
(in words: ethanol reacts with oxygen to yield carbon dioxide and water)
Finish What Happens when Ethanol Burns:Complete “Molecular Models for Ethanol Burning Worksheet Part C & D
Complete “Explanation Tool: What happens when ethanol burns?”• Combine everything you learned about what happens when
ethanol burns into one explanation• Consider evidence from the investigation and observations
from the modeling activity
(15 Minutes)
Molecular Modeling: Methane Burning
You can use what you know about Ethanol burning to explain
many other molecules burning too!
Same Rules for Atoms and Energy Apply
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The bottom of flame at atomic-molecular scale
Oxygen
Carbon Dioxide
Water
Methane
Nitrogen
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The top of flame at atomic-molecular scale
Oxygen
Carbon Dioxide
Water
Methane
Nitrogen
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What happened between the bottom and the top of the flame?
Bottom of the flame
Top of the flame
Oxygen
Carbon Dioxide
Water
Methane
Nitrogen
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Oxygen
Carbon Dioxide
Water
Methane
What’s the hidden chemical change
when methane burns?
?
Always answer the 3 Qs
Whenever you explain a chemical change (reaction)
Use the next slide to help you practice answering the 3 Qs for Methane Burning
Three Questions Poster
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Question Rules to Follow Connecting Atoms to Evidence
The Movement Question: Where are atoms moving?
Where are atoms moving from?Where are atoms going to?
Atoms last forever in combustion and living systems.
All materials (solids, liquids, and gases) are made of atoms.
When materials change mass, atoms are moving.
When materials move, atoms are moving.
The Carbon Question: What is happening to carbon atoms?
What molecules are carbon atoms in before the process?
How are the atoms rearranged into new molecules?
Carbon atoms are bound to other atoms in molecules.
Atoms can be rearranged to make new molecules.
The air has carbon atoms in CO2.Organic materials are made of
molecules with carbon atoms:• foods• fuels• living and dead plants and
animals.
The Energy Question: What is happening to chemical energy?
What forms of energy are involved?How is energy changing from one
form to another?
Energy lasts forever in combustion and living systems.
C-C and C-H bonds have more stored chemical energy than C-O and H-O bonds.
We can observe indicators of different forms of energy:
• organic materials with chemical energy
• light• heat energy• motion.
Making the Reactant Molecules: Methane and Oxygen
Read Part A
Complete Part B.1a-c
Put ALL extra pieces away!!!
Then check your work with Ms KL before continuing
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Photo of reactant molecules: CH4 (methane) and O2 (oxygen)Start by making the molecules and energy units of the reactants and putting them on the reactants side, then rearrange the atoms and energy units to show the products.
Remember: Atoms last forever (so you can rearrange atoms into new molecules, but can’t add or subtract atoms). Energy lasts forever (so you can change forms of energy, but energy units can’t appear or go away)
Reactants Products
Chemical change
Oxygen
Methane
Important:
When you are finished constructing the reactants, put all extra pieces away.
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Rearranging the Atoms to Make Product Molecules: Carbon Dioxide and Water
Complete Steps B.2.a-c
Check with Ms KL before continuing
Complete Steps C & D
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Photo of product molecules: H2O (water) and CO2 (carbon dioxide)Start by making the molecules and energy units of the reactants and putting them on the reactants side, then rearrange the atoms and energy units to show the products.
Remember: Atoms last forever (so you can rearrange atoms into new molecules, but can’t add or subtract atoms). Energy lasts forever (so you can change forms of energy, but energy units can’t appear or go away)
Reactants Products
Chemical change
Water
Carbon dioxide
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Comparing photos of reactant and product moleculesStart by making the molecules and energy units of the reactants and putting them on the reactants side, then rearrange the atoms and energy units to show the products.
Remember: Atoms last forever (so you can rearrange atoms into new molecules, but can’t add or subtract atoms). Energy lasts forever (so you can change forms of energy, but energy units can’t appear or go away)
Reactants Products
Chemical change
Water
Carbon dioxide
Oxygen
Methane
Reactants
Products
Chemical change
What happens to atoms and energy when methane burns?
Methane
Oxygen
Water
Heat and light energy
Carbon Dioxide
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Reactants
Products
Chemical change
Oxygen
Water
Heat and light energy
Carbon Dioxide
What happens to carbon atomswhen methane
burns?
Methane
Carbon atoms in methane become
part of carbon dioxide molecules.
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Reactants
Products
Chemical change
Oxygen
Water
Heat and light energy
Carbon Dioxide
Methane
What happens to oxygen atomswhen methane
burns?
Oxygen atoms become part of
carbon dioxide and water molecules.
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Reactants
Products
Chemical change
Oxygen
Water
Heat and light energy
Carbon Dioxide
Methane
What happens to hydrogen atoms
when methane burns?
Hydrogen atoms become part of
water molecules.
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Reactants
Products
Chemical change
Oxygen
Water
Heat and light energy
Carbon Dioxide
Methane
What happens to chemical energy
when methane burns?
Chemical energy is transformed into heat
and light energy.
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Reactants
Products
Chemical change
What happens to atoms and energy when ethanol burns?
Ethanol
Oxygen
Water
Heat and light energy
Carbon Dioxide
Atoms last forever! Energy lasts
forever!
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Writing a Chemical Equation• Chemists use chemical equations to show how atoms of reactant
molecules are rearranged to make product molecules
• Writing the equation in symbols: Chemists use an arrow to show how reactants change into products:[reactant molecule formulas] [product molecule formulas]
• Saying it in words: Chemists read the arrow as “yield” or “yields:”[reactant molecule names] yield [product molecule names]
• Equations must be balanced: Atoms last forever, so reactant and product molecules must have the same number of each kind of atom
• Try it: can you write a balanced chemical equation to show the chemical change when methane burns?
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Chemical equation for methane burning
CH4 + 2O2 CO2 + 2 H2O
(in words: methane reacts with oxygen to yield carbon dioxide and water)
Homework:
Complete “Molecular Models for Methanol Burning Worksheet Part C & D”
Complete “Explanation Tool: What happens when Methanol burns?”• Combine everything you learned about what happens when
methanol burns into one explanation• Consider evidence from the investigation about ethanol and
observations from the methanol modeling activity
