1. An Introduction to Energy Unit 2, Presentation 1

2. What is Energy?  Energy is defined as the ability to do work Work is any force applied over a distance

3. Six Different Types of Energy Type of EnergyField of Study HeatThermodynamics SoundAcoustics Light (Electromagnetic Radiation) Optics ChemicalChemistry ElectricalElectromagnetism Mechanical (Kinetic & Potential) Mechanics *Nuclear Energy is a special case*

4. SI Unit for Energy  Energy is measured in Joules (J) Named in honor of James Joule (British)  Can also be measured in Calories (cal) One calorie = amount of energy needed to warm one gram of water one Kelvin. One calorie ~ 4.20 Joules

5. Conservation of Energy & Mass  Energy is neither created nor destroyed in a chemical reaction  Mass is neither created nor destroyed in a chemical reaction

6. Types of Chemical Reactions  Exothermic: A chemical reaction that releases heat energy. Expressed as the following: Reactants  Products + Energy  Endothermic: A chemical reaction that absorbs heat energy. Endothermic reactions require heat energy to be completed. Expressed as the following: Reactants + Energy  Products

7. Heat Energy and Temperature  Temperature is a measure of heat energy Three measures of temperature:  Degrees Fahrenheit  Degrees Celsius  Kelvin (Absolute Temperature)

8. Comparison of Three Temperature Scales Fahrenheit Scale Celsius Scale Kelvin Scale Boiling Point of Water 212100373 Body Temperature 98.637310 Freezing Point of Water 320273 Absolute Zero -460-2730

9. Making a Celsius Thermometer

10. Converting to Kelvin  The Absolute Temperature (Kelvin) scale is most often used K = °C + 273.16 Hence, 0.0000°C = 273.16K

11. Calorimetry  Calorimetry: The measurement of the amount of heat released or absorbed during a chemical reaction.

12. Calorimetry Example  A 2000. gram mass of water has its temperature raised 3.0°C while an exothermic chemical reaction is taking place. How much heat is transferred to the water by the heat of the reaction (the specific heat of water is 4184 J/kg K)?

13. Another Calorimetry Example  A 1000. gram mass of water whose temperature was 50.0°C lost 33 600 J of heat over a 5-minute period. What was the temperature of the water at the end of the 5-minute period? Use the same specific heat of water as the previous example.

14. Kinetic Theory of Heat & Temperature  Heat energy, measured by temperature, is directly proportional to the average kinetic energy of the molecules in the substance. As temperature increases, so does the average speed of the molecules in the substance As temperature decreases, so does the average speed of the molecules in the substance.

15. More Kinetic Theory Matter consists of atoms and molecules in motion. v SolidLiquidGas Low Energy Moderate Energy High Energy Slow Molecules Fast Molecules Slow vibratory motions Still mostly vibrations, but slightly faster