1) Physical and chemical changes in matter involve transfers of energy. Energy can move or change objects and form new compounds. It is always involved in changes of matter. 2) The law of conservation of energy states that energy cannot be created or destroyed, just changed from one form to another. Changes can be endothermic, absorbing energy, or exothermic, releasing energy. 3) Heat is the energy transferred between objects, while temperature is a measure of the average kinetic energy of particles. Heat is involved in both physical and chemical changes, but does not necessarily affect the temperature.

1. Chapter 2.1 : Energy Matter and Energy

2. Objective 1 : Explain that physical and chemical changes in matter involve transfers of energy Energy : capacity to do work Move an object Form a new compound Generate light Always involved in a change of matter. Physical change : change matter from 1 form to another without changing identity of substance. Water boiling Evaporation Wax melting Chemical Change : change in matter into entirely new substance. Combustion of candle – Changed into CO2 and H2O

3. Matter and Energy

4. Objective 2 Apply the law of conservation of energy to analyze changes in matter Law that states that energy cannot be created or destroyed, just changed from 1 form to another. 2 Types of processes Endothermic : energy is absorbed Example: melting ice, ice pack Exothermic : energy is released Example: freezing of water, Explosive reactions (TNT) System : part being studied Ice cube Surroundings : everything else air around ice cube Transfer of energy in different forms Photosynthesis Light stick Combustion in a car

5. Exothermic and Endothermic Changes

6. Objective 3 Distinguish between heat and temperature. Heat : energy transferred between objects Ice cube melting on a hot day – physical change Candle burning – chemical change Energy released as heat Grandcamp explosion Kinetic energy – energy of motion Energy absorbed as heat Baking powder in a cake 2NaHCO3 Na2CO3 + H2O + CO2 Heat is needed for reaction to occur Temperature Measure of the average kinetic energy of the particles in an object

7. Heat versus Temperature

9. Absolute zero – all particle movement stops

11. Affects substances differently Specific heat : Quantity of heat needed to raise a certain mass of substance 1 oC Express in (J/g.K) Examples: Water – high specific heat Metal – low specific heat Transfer of heat