14.3 Energy and Reactions
Energy and Reactions Energy is involved in chemical reactions… to break bonds in the reactants AND 2. to form new bonds to make new products
Endothermic Reactions Endothermic reaction: forming new bonds requires energy endo = energy “in” Endothermic reactions will get colder.
Examples of Endothermic Reactions Photosynthesis: Cold packs:
Exothermic Reactions exo = energy “exits” Exothermic reaction: forming new bonds releases energy exo = energy “exits” Exothermic reactions will get hotter.
Check in! Classify each as endothermic or exothermic: When activated, a cold pack gets colder A fire gives off heat A candle burns Endo, Exo, Exo
Activation Energy Activation energy: the energy needed to begin a reaction and break chemical bonds in the reactants Example: http://www.youtube.com/watch?v=9rR6OEQRFZQ
Reaction Coordinate Diagram Show the energy changes throughout a reaction Activation Energy Energy Products Energy change for the reaction Reactants Reaction progress
Reaction Coordinate Diagram Endothermic reactions require energy -Higher energy after reaction than before Exothermic reactions give off energy -Lower energy after reaction than before
Potential Energy Is this an example of an endothermic reaction or an exothermic reaction?