Potential Energy Diagrams for Chemical Reactions, Lecture notes of Physics

Download Potential Energy Diagrams for Chemical Reactions and more Lecture notes Physics in PDF only on Docsity! Potential Energy Diagrams 2018.notebook 1 April 25, 2018 Mar 4­1:54 PM Potential Energy Diagrams Aim: To analyze the change in PE for a reaction. Mar 4­6:48 PM Energy changes and Diagrams • Every chemical reaction will either absorb or release energy. • A potential energy diagram shows the change in energy during a reaction. • Heat of Reaction, ΔH: the overall difference in potential energy between the products and the reactants. ΔH = PEPRODUCTS - PEREACTANTS Endothermic Exothermic ΔH = + (overall gain) ΔH = - (overall loss) Energy is absorbed Energy is released Mar 4­6:48 PM Energy changes and Diagrams Endothermic Exothermic ΔH = + (overall gain) ΔH = - (overall loss) Energy is absorbed Energy is released Reaction Reaction P. E. P. E.Reactants Products Reactants Products Apr 24­10:45 AM ELEPHANTS TOOTHPASTE Potential Energy Diagrams 2018.notebook 2 April 25, 2018 Apr 24­10:51 AM 4. Below is a sketch of the potential energy diagram for the decomposition reaction of hydrogen peroxide. ∙ Label the location of the reactants and products. ∙ Label the ΔH, and the activation energy. ∙ Indicate the addition of a catalyst on the potential energy diagram curve using a dashed line. Apr 14­9:51 AM Mar 5­10:04 AM Products A + B  C + D  Po te nt ia l E ne rg y Reaction Pathway Reactants 100 150 200 250 300 350 400 450 500DIAGRAM #1  Reaction:   A + B         C + D + Heat 1. What is the potential energy of the reactants? 2. What is the potential energy of the products? 3. In the potential energy diagram above, what is the activation energy of the  forward reaction? 4. What is the ΔH (total energy change) of the reaction?  Is this reaction  endothermic or exothermic? Mar 5­10:04 AM Products A + B  C + D  Po te nt ia l E ne rg y Reaction Pathway Reactants 100 150 200 250 300 350 400 450 500DIAGRAM #1  Reaction:   A + B         C + D + Heat 1. What is the potential energy of the reactants? 2. What is the potential energy of the products? 3. In the potential energy diagram above, what is the activation energy of the  forward reaction? 4. What is the ΔH (total energy change) of the reaction?  Is this reaction  endothermic or exothermic? 350 kJ 150 kJ 500‐350= 150 kJ 150‐350= ‐200 kJ; exothermic