2/10/2014

1. 2/10/2014 What is the law of conservation of mass? So what do you think the law of conservation of ENerGYis?

2. Today’s Goal I can use chemical and physical changes to recognize chemical reactions.

3. Today’s Plan • Discuss the Law of Conservation of Energy • Lab Conclusions *Review on Tuesday **Chemistry Test Wednesday

4. Write down the underlined phrases and 1 example of each type of energy

5. Energy • Energy = Ability to do work; • Energy = A source of useable power

6. What are the six different types of energy? • Mechanical: Energy from motion (or position) • What types of things have mechanical energy?

7. Other types of energy… • Chemical: Energy that is stored • What has chemical energy?

8. Other types of energy… • Thermal: Energy from heat! • What has thermal energy?

9. Other types of energy… • Electrical and Electromagnetic: Energy from charges (electrons). • What has electric or magnetic energy?

10. Other types of energy… • Nuclear: energy from atoms.

11. Converting Energy • Mrs. Gardner ran 3 miles last night. What kind of energy is “running?” • Running = Movement = Mechanical Energy! • Where did Gardner get the energy to run? • Food = Stored energy = Chemical Energy! • Where did the food get its stored energy? • Sun = heat = Thermal Energy! We traced this pathway BACKWARDS…but understand that all energy starts with the sun!

12. Sun—Gives off heat which is Thermal Energy Plant—Makes Fruit that is full of Chemical Energy Bird—Chews the fruit using Mechanical Energy Sweat and Heat—Released to atmosphere through Thermal Energy Bird—Flies using Mechanical Energy Fruit—Food gets stored as Chemical Energy in the bird

13. Key—Turned to on position using Mechanical Energy Battery—Uses stored Chemical Energy to ignite the engine Foot—Presses gas pedal using Mechanical Energy Gasoline—Releases stored Chemical Energy into the engine Car—Drives to the mall using Mechanical Energy Engine—Pistons start pumping creating Mechanical Energy

14. Remember the Law of Conservation of Energy • Chemical reactions need energy to happen • That energy cannot disappear

15. Exothermic reaction: a change that releases heat. EXothermic = Exit Feels Hot

16. Endothermic reaction: a change that requires (or absorbs) heat. ENdothermic= Enter (Feels Cold) Photosynthesis is an endothermic reaction (requires energy input from sun)

17. reaction reaction Measuring Heat Exothermic reaction, heat given off & temperature of water rises Endothermic reaction, heat taken in & temperature of water drops

18. Law of Conservation of energy Examples • Running: Motion energy changes into heat energy • Singing: Motion energy changes into sound energy • Cooking: Chemical energy and heat energy change into chemical energy

19. How to make a reaction happen faster

20. Chemical Reactions occur because particles are moving • Everything is made of particles. • The more these particles run into each other, the faster the reaction.

21. There are ways to make particles hit each other more • Increasing temperature • By increasing the temperature, you are adding more energy to the particles • Adding more energy makes the particles move faster • The more candy you give middle school students, the more active they become • Adding energy to a liquid makes the particles move faster to become a gas

22. There are ways to make particles hit each other more 2. Increasing surface area • By increasing the surface area, you are creating more places for particles to hit each other

23. Surface Area If the particles are going fast enough to react, the next step is to allow it to react with as much material as it can.

24. Inhibitor An inhibitor is a substance that slows down or stops a chemical reaction Examples: • Antibiotics stop the reaction needed for bacteria to make cell walls • Preservatives in food slow down the process of going bad