02 Notes - Endo and Exo Reactions

02 Notes - Endo and Exo Reactions - Very unstable Lasts for...

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Aim: What information can be obtained from a potential energy diagram? QQ: Why does the temperature of a substance maintain the same during a phase change? Do Now: What is energy? Brainstorm as many different types of energy as you can. Thermodynamics: the study of energy conversions What role does heat play in chemical and physical changes? Is heat a reactant or a product? System: the substance that is being studied Surroundings: everything outside of the system, the environment Always evaluate the surroundings! It is too difficult to determine what is going on with the system! First Law of Thermodynamics: The energy of the universe is constant…energy can neither be created nor destroyed, it can only change forms. Energy lost by the system = Energy gained by the surroundings Potential Energy Diagrams Activation Energy (E A ) Energy required to start a reaction Every reaction requires this energy Like the hill at a beginning of a roller coaster… Transition State (T s ) High energy intermediate
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Unformatted text preview: Very unstable Lasts for an extremely short period of time Change in Enthalpy ( H) Heat of the reaction Represents energy Can be positive or negative H = products - reactants Exothermic Reactions: Reactions that release heat/energy into the surroundings. Products have less energy than the reactants (- H) The system loses energy as the reaction progresses A+B AB + heat Endothermic Reactions: Reactions that absorb heat/energy from the environment Products have more energy than reactants (+ H) The system gains energy as the reaction progresses Heat + A + B AB Conclusions: Energy of the universe is constant System is the reaction itself, surroundings is everything else (environment) Exothermic Reactions: release energy, products have less energy than reactants, heat is a product Endothermic Reactions: absorb energy, products have more energy than reactants, heat is a reactant...
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02 Notes - Endo and Exo Reactions - Very unstable Lasts for...

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