Post on 23-Dec-2015
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?
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
2H2 + O2 -> 2H2O
Write this equation in words …
Cold Calls:1) What are the reactants?2) What is the product?
4. Burning of Hydrogen Gas
2H2 + O2 -> 2H2O
Write this equation in words …
Two molecules of hydrogen react with one molecule of oxygen to make water!
Burning Hydrogen Gas
http://www.youtube.com/watch?v=WT5MGUyoTxc
5. Think/Pair/Share: What kind of a reaction is this? How do you know?
Energy Sources6. 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?
C6H12O6 + O2 -> H2O + CO2
Breaking and Making Bonds
10. Breaking chemical bonds CREATES ENERGY.Energy is released in the form of heat, so this is an EXOTHERMIC 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
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
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?
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!