Topic: Energy and Rates of Chemical Reactions PSSA: A / S8.C.1.1

Objective: TLW compare endothermic and exothermic reactions TLW compare endothermic and exothermic reactions TLW describe four ways that the rate of a chemical reaction can be changed. TLW describe four ways that the rate of a chemical reaction can be changed.

MI #1: Endothermic vs. Exothermic Energy is a part of all chemical reactions. Energy is a part of all chemical reactions. Reactions in which energy is released are called exothermic reactions. Reactions in which energy is released are called exothermic reactions. Reactions in which energy is absorbed are called endothermic reactions. Reactions in which energy is absorbed are called endothermic reactions.

MI #2: Law of Conservation of Energy The Law of Conservation of Energy states that energy cannot be created or destroyed in a chemical reaction, it can only change forms. The Law of Conservation of Energy states that energy cannot be created or destroyed in a chemical reaction, it can only change forms.

MI #3: Activation Energy Before a chemical reaction can begin, it must get a boost of energy. Before a chemical reaction can begin, it must get a boost of energy. The smallest amount of energy required to start a chemical reaction is called activation energy. The smallest amount of energy required to start a chemical reaction is called activation energy.

MI #4: Rates of Reactions Reaction rate is a measure of how fast a chemical reaction takes place. Reaction rate is a measure of how fast a chemical reaction takes place. Changing different factors involved with a reaction can change the rate of the reaction. Changing different factors involved with a reaction can change the rate of the reaction.

MI #5: Factors Affecting the Rate of a Chemical Reaction (Part 1) Temperature – Higher temperature results in more molecular collisions and a faster reaction rate. Temperature – Higher temperature results in more molecular collisions and a faster reaction rate. Concentration – Increased concentration of reactants results in more molecular collisions and a faster reaction rate. Concentration – Increased concentration of reactants results in more molecular collisions and a faster reaction rate.

MI #6: Factors Affecting the Rate of a Chemical Reaction (Part 2) Surface Area – Increasing the amount of exposed surface of solid reactants increases reaction rates. Surface Area – Increasing the amount of exposed surface of solid reactants increases reaction rates. Catalysts – A substance that speeds a reaction without being used up. Catalysts – A substance that speeds a reaction without being used up. Inhibitor – A substance that slow a chemical reaction. Inhibitor – A substance that slow a chemical reaction.

So What…? Real Life Application Understanding the Law of Conservation of Energy is foundational to understanding energy conversions. Understanding the Law of Conservation of Energy is foundational to understanding energy conversions. Understanding what affects the rate of a chemical reaction is important because it allows us to change how fast chemical reactions occur. Understanding what affects the rate of a chemical reaction is important because it allows us to change how fast chemical reactions occur.