CHEMICAL REACTIONS VACHS BIOLOGY

DO NOW: 1)What is a disaccharide? 2)What macromolecule do amino acids make up? 3)Glycerol and fatty acids combine to make what kind of macromolecule? 4)What is DNA composed of?

What is a chemical reaction? Do we have any connections to the words “chemical reactions?”

1. A chemical reaction is a process that changes one set of chemicals into another. 2. Chemical reactions involve changes in the chemical bonds that join atoms in compounds.

Examples of Chemical Reactions Think/Pair/Share: Discuss any examples of chemical reactions that you have performed or that we have studied in this class.

3. Physical Reaction vs Chemical Reaction PHYSICAL REACTION: causes a phase change (think of some examples…). CHEMICAL REACTION: causes changes in chemical bonds.

4. Burning Hydrogen Gas 2H 2 + O 2 -> 2H 2 O Write this equation in words … Cold Calls: 1)What are the reactants? 2)What is the product?

4. Burning of Hydrogen Gas 2H 2 + O 2 -> 2H 2 O Write this equation in words … Two molecules of hydrogen react with one molecule of oxygen to make water!

Burning Hydrogen Gas Txc 5. Think/Pair/Share: What kind of a reaction is this? How do you know?

Energy Sources 6. What REACTION do plants use to create their energy source (glucose)? 7. How do animals obtain their energy source (glucose)? 8. What reaction do both plants and animals use to make energy out of their ENERGY SOURCES?

Breaking and Making Bonds

In the process of cellular respiration, both plants and animals break down GLUCOSE and convert it into energy. 9. The bonds are being broken in WHICH MOLECULES? C 6 H 12 O 6 + O 2 -> H 2 O + CO 2

Breaking and Making Bonds 10. Breaking chemical bonds CREATES ENERGY. Energy is released in the form of heat, so this is an EXOTHERMIC REACTION.

11. Making chemical bonds REQUIRES ENERGY. Energy is needed, so this is an ENDOTHERMIC REACTION.

ACT IT OUT!!! WHEN I SAY GO….. Find a partner and link arms with them! 1.First demonstrate what happens to chemical bonds during an exothermic reaction. 2.Then demonstrate what happens to chemical bonds during an endothermic reaction!

Making and Breaking Bonds THINK/PAIR/SHARE: 12. What kind of a reaction is cellular respiration?

Making and Breaking Bonds CELLULAR RESPIRATION IS EXOTHERMIC!! The chemical bonds in the glucose and oxygen molecules are being broken down to release energy (heat!).

HOT AND COLD PACKS? TWO VOLUNTEERS TO START THESE CHEMICAL REACTIONS …

HOT AND COLD PACKS HOT: EXOTHERMIC! You can feel the heat being released. COLD: ENDOTHERMIC! You can feel the loss of heat. Remember…. There is no “cold.” Only the absence of heat!

Activation Energy 13. Activation Energy: the energy that is needed to get a reaction started! THINK/PAIR/SHARE: When you are burning paper, what happens before it turns into smoke?

Activation Energy Diagrams (…Diagram on the board. )

Label the Graphs: Endothermic or Exothermic?

On the back of your paper… Draw an activation energy diagram for CELLULAR RESPIRATION. Draw an activation energy diagram for PHOTOSYNTHESIS.

Endothermic/Exothermic Lab Voices/Movement: “restaurant voices,” one person moves in order to get materials. Instructions: Listen to the instructions I am going to give and follow the instructions on your lab sheets! Success: Finish your lab, answer your questions and clean up within the time allowed!

Finish Labs & Text Questions Make sure to turn in your lab sheets at the front of class and start working on your text support questions!