2. Just What Is It

3. How Can We Define Energy The capacity to do work Or the ability to cause a change to occur

4. What Are the Types of Energy? Electrical Chemical Heat Solar Sound Gravitational Magnetic Kinetic energy

5. Law of Conservation of Energy Energy can neither be created or destroyed Energy is a quantity that can be stored in fields Energy can be transfer from one field to another with no loss of energy The energy lost in one area will lead to an increase in heat in another area The only problem is that the energy is not always transferred into energy that you wish

6. What About in a Car What does the energy start out as? Chemical energy What type of energy do we wish to get out? Kinetic energy Most of the energy from gas get transfer to what type of energy Heat

7. What Is Heat? The warmer an object is the more the particles move Temperature is the measurement of the kinetic energy of the particles No such thing as cold scientifically- just the absence of heat

8. Energy Transfers Involving Heat Exothermic An event when heat energy is lost to the environment Examples; Fire and steam condensing

9. Energy Transfers Involving Heat Endothermic An event in which heat energy is removed from the environment Energy is taken in Examples ice melting An ice pack Why if endothermic reactions take in heat do they feel cold What happens to the energy?

10. Heat Potential Energy Heat potential energy is measured in calories; C A calorie is defined as the amount of heat needed to raise the temperature of 1 gram of water 1 degree C How much energy is need to heat 10 grams of water from 20C to 30C? The calories listed on nutrient labels are kilocalories, C

11. Specific Heat Capacity Every substance has its own ability to absorb heat Water’s specific heat is 1c/g Is this a physical or chemical property? Specific heat is often listed as j/gc J joule where 1 cal = 4.184 joules

12. Specific Heat Capacities Specific Heat Capacity is a physical property of a substance The specific heat capacity changes depending on the phase of matter Heat capacity of ice 2.1J/gC Heat capacity of water 4.184J/gC Heat capacity of steam 1.7J/gC

13. Specific Heats Al.9 J/g/C Cu.385J/g/C Gold.129J/C Fe.449J/gC Water 4.184 J/gc

14. Calculating Heat The heat needed to change the temperature of an object can be easily calculated by this formula Q= mcΔT Q = heat gained or lost m = mass c = specific heat ΔT = change in temperature

15. Warming Ice How much heat is needed to heat an ice cube with a mass of 10 grams of from -10C to 0C? Heat= mc  T Heat = 10g (2.1j/gC) 10C Heat = 210J Not the same for all ice cubes

16. Phase Changes The particles of a substance change energy when a phase change occurs It can gain energy What happens to the temperature of a substance as it gains energy

17. Names of Phase Changes Solid to liquid Melting Liquid to gas Evaporation Solid to gas Sublimation Liquid to solid Freezing Gas to liquid Condensation Gas to Solid Deposition

18. What happened to D.W.’s Snowball? D.W. saved a snowball in the back of the freezer. She checked on it regularly One day she looked and it was gone What happened? Water will sublime Solid to gas very slowly

19. Heat of Fusion Heat of fusion is the amount of heat needed to turn 1 gram of a solid into a liquid For ice 335j/g Cesium 15.7j/g Magnesium 372j/g

20. Heat of Vaporization Heat needed to turn 1 gram of a substance from liquid to a gas Water 2260 j/g Oxygen 213 j/g Aluminum 10,540j/g

21. Interesting Fact to Remember The temperature is constant during a phase change Water will stay at 0C until all the ice is melted Water will stay at 100C until all the water is boiled away

22. Temperature Vs Heat Graphs Ice Melting Water Boiling Steam

23. Calculating Heat Added With 10 Grams H 2 0 Starting at –10C 210J 3350J 10gX335j/g 4184J 22,600J 10g x 2260J/g Ending at 110C 170J Total Heat Needed 66,004J

24. Heat of Combustion Heat of combustion lists the amount of energy given off when something burns The heat of combustion can be calculated easily for many substances The nutrient labels are based upon the heat of combustion of the ingredients

25. Heat of Combustion The heat given off when burning 1 gram of a substance Determined using a calorimeter