1. Chemistry—Chapter 2 ENERGY

2. What is ENERGY? (list types of energy) The ability to do WORK. What is WORK? The ability to move something, create a new compound or generate light.

3. Energy is neither Created nor Destroyed. Energy isn’t really lost or gained—it is TRANSFERRED to the System and its Surroundings.

4. What is the System? What is the Surroundings? Where is the energy transfer?

5. http://www.youtube.com/watch?v=s- KvoVzukHo http://www.youtube.com/watch?v=s- KvoVzukHo Movement of the molecules requires energy. So which state requires the most energy?

6. Chemical Changes Remember that changes of state are PHYSICAL changes, while CHEMICAL changes actually change the substance. In order for a CHEMICAL change to occur, there must be CONSERVATION of ENERGY. THE LAW of CONSERVATION of ENERGY states that “ENERGY is neither CREATED nor DESTROYED”.

7. Conservation of ENERGY When a Physical change happens, for example, a Phase change, energy is either absorbed or released. The same is true for a Chemical change. – If energy is released it is EXOTHERMIC – If energy is absorbed it is ENDOTHERMIC EXOTHERMIC—gets hot! ENDOTHERMIC—gets cold!

8. Remember to look at the SYSTEM and its SURROUNDINGS For example, when RUST happens (oxygen combines with iron), this is an Exothermic process, but if you walk outside and touch something rusty it doesn’t feel warm. WHY?

9. Why? The heat is given off to the ATMOSPHERE (the surroundings). It is very hard to detect a tiny increase in HEAT in a giant atmosphere. Its like adding a teaspoon of salt to a cup of water or an ocean. Would you detect the salt increase in the ocean?

10. One type of ENERGY is HEAT Heat is energy transferred from one object to another which makes molecules move. Heat always moves from a HOT object to a Cooler one. One cannot transfer COOLness. – Why do icecubes in a glass of water melt?

11. Exothermic Reactions Explosions are Rapid Releases of Heat. Energy can be stored (potential energy) as CHEMICAL ENERGY and released during a reaction as KINETIC ENERGY.

12. http://www.youtube.com/watch?v=GyVD8V00 16w

13. Endothermic Reactions Ice Packs that get cold when you break them are ENDOTHERMIC—they absorb heat when a reaction inside the bag occurs.

14. http://www.youtube.com/watch?v=YL- uS7kMa0I

15. HEAT IS DIFFERENT than TEMPERATURE!! Temperature is the AVERAGE energy of molecules in a substance. Some molecules will have more energy and others less, but the AVERAGE is the temperature.

16. Changes of State

17. What is KELVIN ? Farhenheit Celsius Kelvin - 459 -273 0 32 0 273 212 100 373 Water Boils Ice Melts “Absolute 0”

18. How to calculate Kelvin/Celsius Every degree Celsius can be converted to Kelvin by ADDING 273. – Example: 0 Celsius = 273 Kelvin Every degree Kelvin can be converted to Celsius by SUBTRACTING 273. – Example: 373 Kelvin = 100 Celsius