1. Endothermic and Exothermic Reactions

2. Curriculum Big Idea: Changes in matter are accompanied by changes in energy. Competency: Demonstrate how changes in matter are accompanied by changes in energy. PA Standard 3.2.10.A4: Explain the difference between endothermic and exothermic reactions.

3. Today’s Agenda Opener: What are some units of energy? Go over the homework (12.1 Section Assessment) Investigate endothermic and exothermic reactions when making hot and cold packs. Read the Chem Talk and answer the Checking Up Questions Notes on Exothermic and Endothermic Reactions Closure: Give an example of an endothermic reaction. Take Home Assignment: Chemistry to Go – page 185

4. Cool Chemistry Show: Activity 5 Energy and Chemical Change

5. Energy is... The ability to do work. Work is a force acting over a distance. Heat is energy transferred between objects because of temperature difference. Two types of energy: 1. Kinetic-energy of motion 2. Potential-due to the composition or position of any object, energy is stored

6. Energy B. Law of conservation of energy- in any chemical reaction or physical process, energy can be converted from one form to another, but is neither created nor destroyed C. Chemical Potential Energy- energy stored in a substance because of its composition

7. The universe is divided into two halves. the system and the surroundings. System: the part of the universe we are concerned with Surroundings: everything else in the universe

8. Exothermic/Endothermic Exothermic  Heat flows out of system  Heat Exits Endothermic  Heat flows into system  En=In

9. Important Vocab Activation Energy  Energy required for reaction to start Catalyst  Chemical that lowers the activation energy Heat of Reaction  The difference between products and reactants

10. Potential energy Heat Exothermic

11. Potential energy Heat Endothermic

12. Chem Words Endothermic change or reaction: a change in which energy in the form of heat is absorbed from the surrounding environment resulting in an increase in the internal energy of the system Exothermic change or reaction: a change in which energy in the form of heat is released from a system resulting in a decrease in the internal energy of the system. Temperature: the measure of the average kinetic energy of all the particles of the material.