Modeling & Explaining Ethanol Burning Carbon TIME Modeling & Explaining Ethanol Burning

What do you think happens when methane burns? Entry Task: Methane is CH4 What do you think happens when methane burns? Include answers to the movement, carbon and energy questions in your answer

Three Questions Poster 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.

The bottom of flame at atomic-molecular scale Credits: Craig Douglas, Michigan State University Oxygen Carbon Dioxide Water Methane Nitrogen

The top of flame at atomic-molecular scale Credits: Craig Douglas, Michigan State University Oxygen Carbon Dioxide Water Methane Nitrogen

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 Credits: Craig Douglas, Michigan State University K

What’s the hidden chemical change when methane burns? Credits: Craig Douglas, Michigan State University Oxygen Carbon Dioxide Water Methane

Making the Reactant Molecules: Methane and Oxygen Read Part A Complete Part B.1a-c Put ALL extra pieces away!!! Show Ms KL your Reactants before moving on to part B.2

Chemical change Methane Oxygen 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. Chemical change Methane Photo Credit: Michigan State University Oxygen Reactants 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)

Important: When you are finished constructing the reactants, put all extra pieces away.

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

Water Chemical change Carbon dioxide 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. Water Chemical change Carbon dioxide Photo Credits: Michigan State University Reactants 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)

Comparing photos of reactant and product molecules 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. Water Chemical change Carbon dioxide Methane Photo Credits: Michigan State University 3. (Optional) Have students use molecular models and twist ties to show changes in matter and energy.  Have students continue working in pairs to show how the matter and energy in methane and oxygen can be rearranged into the molecules of the products: carbon dioxide and water. Tell students that the product molecules have no high-energy bonds, so the chemical energy in the methane is transformed into heat and light energy. Use Slide 6 and the instructions on the worksheet to assist students in constructing a model of the chemical reaction. Have students use the same materials they used to form their reactant molecules to form the product molecules. Tell them to place their products in the appropriate box on the product side of the poster. Show Slide 7 to let students compare their products to the products in the picture. Have students use new energy cards (heat and light) to indicate what form the energy is in after the chemical change by putting the card under the twist ties. Show Slide 8 to give students an overview of the entire reaction. Oxygen Reactants 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)

What happens to atoms and energy when methane burns? Carbon Dioxide Methane Reactants Chemical change Credits: Craig Douglas, Michigan State University Water Products Oxygen Heat and light energy

What happens to carbon atoms when methane burns? Carbon Dioxide Methane Reactants Chemical change Credits: Craig Douglas, Michigan State University Water Products Carbon atoms in methane become part of carbon dioxide molecules. Oxygen Heat and light energy 15

What happens to oxygen atoms when methane burns? Carbon Dioxide Methane Reactants Chemical change Credits: Craig Douglas, Michigan State University Water Products Oxygen atoms become part of carbon dioxide and water molecules. Oxygen Heat and light energy

What happens to hydrogen atoms when methane burns? Carbon Dioxide Methane Reactants Chemical change Credits: Craig Douglas, Michigan State University Water Products Hydrogen atoms become part of water molecules. Oxygen Heat and light energy

What happens to chemical energy when methane burns? Carbon Dioxide Methane Reactants Chemical change Credits: Craig Douglas, Michigan State University Water Products Chemical energy is transformed into heat and light energy. Oxygen Heat and light energy

What happens to atoms and energy when ethanol burns? Carbon Dioxide Ethanol Reactants Chemical change Credits: Craig Douglas, Michigan State University Water Products Atoms last forever! Energy lasts forever! Oxygen Heat and light energy

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?

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