2. Thermal Energy A. Temperature & Heat 1. Temperature is related to the average kinetic energy of the particles in a substance.

3. 2. SI unit for temp. is the Kelvin a. K = C + 273 (10C = 283K) b. C = K – 273 (10K = -263C) 3. HEAT Energy – the total of all the kinetic and potential energy of all the particles in a substance.

4. Types of energy POTENTIAL ENERGY : STORED ENERGY. The energy inside the substance. KINETIC ENERGY : Associated with motion. Average KE = TEMPERATURE

5. Energy The ability to do work. You measure energy in joules (J). Exothermic- energy given off in a chemical reaction. Endothermic- energy absorbed in a chemical reaction.

6. FORMS OF ENERGY Chemical Energy- Energy released or absorbed in a chemical reaction. Ex.= Oil burning (when oil burns, chemical energy is changed into heat energy.) Electrical Energy- Energy of the flow of electrons. Electromagnetic Radiation- Energy made up of waves, which include gamma rays, ultraviolet, light, radio waves, etc. Heat Energy- Random motion of atoms and molecules. Mechanical Energy- Energy in moving objects. Ex.= Rock falling / car moving Nuclear Energy- Energy given off when a nucleus breaks up into smaller nuclei or when smaller nuclei unite to form a larger nucleus.

7. PRINCIPLE OF CONSERVATION OF ENERGY Energy cannot be created nor destroyed. It can be transformed from one form to another or it can transferred from one body to another.

8. HEAT ENERGY What is HEAT? Form of energy and measured in JOULES Visit www.worldofteaching.com for more free powerpointswww.worldofteaching.com

9. Heat and Temperature The temperature of an object tells us how HOT it is Measured in degrees Celsius - °C It is NOT the same as heat energy although the two quantities are related. e.g. a beaker of water at 60 °C is hotter than a bath of water at 40 °C BUT the bath contains more joules of heat energy

10. Heat a. The flow of thermal energy from one object to another. Heat always flows from warmer (HIGH T) to cooler(LOW T) objects. Ice gets warmer while hand gets cooler Cup gets cooler while hand gets warmer

11. Heating and Cooling If an object has become hotter, it means that it has gained heat energy. If an object cools down, it means it has lost energy

12. 6. Specific Heat a. Some things heat up or cool down faster than others. Land heats up and cools down faster than water

13. HEAT CAPACITY The amount of heat needed to increase the temperature of a material by 1 o C. It depends on the MASS and the CHEMICAL COMPOSITION of the material.

14. SPECIFIC HEAT CAPACITY The amount of heat needed to increase the temperature of 1 g of substance by 1 C. Depends only on the chemical composition.

15. HEAT OF FUSION FOR WATER (TABLE B) Amount of heat needed to completely melt 1g of water. 334 J/g 334 Joules of heat are necessary to completely melt 1 g of water. HOW MUCH HEAT IS NEEDED TO MELT 10 g OF WATER?

16. HEAT OF VAPORIZATION FOR WATER (TABLE T) The amount of heat needed to completely vaporize one g of water at its boiling point. 2260 J/g Water needs 2260 J of heat per gram to convert to gas!

17. How to calculate changes in HEAT The heat absorbed or released in a chemical reaction Q = m x  T x Cp Q = HEAT m = mass of substance  T = change in temperature (Tf – Ti) Cp = specific heat of substance

18. Calorimeter

19. Bomb Calorimetry A more sophisticated model is the bomb calorimeter, it has a chamber where a chemical reaction takes place and a device to start the reaction.