Energy and Rates of Chemical Reactions

1. Energy and Rates of Chemical Reactions Chapter 4.4

2. Energy is needed to break bonds • Law Conservation of Energy- Energy cannot be created or destroyed. • It can change forms Reactions and Energy

3. Exo means “exit” • Thermic means “Heat” or “Energy” • Define Exothermic • How does an exothermic reaction feel? Exothermic Reaction

4. Endo means “go in” • Thermic means “heat” or “energy” • Define Endothermic • How does an endothermic reaction feel? Endothermic Reaction

5. Activation Energy: Smallest amount of energy that is required for molecules to react • Striking a match • Friction is a source of activation energy Rates of Reactions

6. Catalyst- speeds up a reaction by lowering the amount of energy needed so that a reaction can happen more easily. • Are not actually part of the products or reactants. Enzymes in the body are catalysts too! Catalyst

7. Inhibitor- slows down a reaction Inhibitor

8. Temperature • At high temperatures, particles of reactants move quickly. • The higher the temperature…… Factors Affecting Rates of Reactions

9. Concentration • A measure of the amount of one substance dissolved in another substance. • There is a small distance between particles with a high concentration • The higher the concentration…… Factors Affecting Rates of Reactions

10. Surface Area • The amount of exposed surface of a substance • Grinding a solid into a powder makes a larger surface area • The greater the surface area…… Factors Affecting Rates of Reactions

11. Inhibitor vs. Catalysts • Inhibitor: substance that slows down or stops a reaction. • Preservatives • Catalyst: substance that speeds up a reaction without being permanently being changed • Not a reactant • Enzymes • Catalytic Converter Factors Affecting Rates of Reactions