04 Notes - Enthalpy

04 Notes Enthalpy - Aim W hat is enthalpy QQ Draw a potential energy diagram for an endothermic reaction and label key aspects Do Now W hy do

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Aim: What is enthalpy? QQ: Draw a potential energy diagram for an endothermic reaction and label key aspects. Do Now: Why do chemists use moles instead of grams when comparing two pure substances? Heat of Fusion: energy required to melt a substance Heat of Vaporization: energy required to vaporize a substance Heat of Fusion q = mH f Heat of Vaporization q = mH v Use the Reference Table B to obtain the values of H f and H v for water. How much energy is required to vaporize 100.0 g of water? Enthalpy: the heat that is absorbed or released in a chemical reaction, takes into account the molar quantity of the reactants (ΔH). ΔH reaction = nΔH products nΔH reactants ΔH is looked at from the perspective of the system… Exothermic Reactions The system loses energy ΔH is negative 2H 2 (g) + O 2 (g) 2H 2 O (l) + 571.6 kJ 2H 2 (g) + O 2 (g) 2H 2 O (l) ΔH = -571.6 kJ Endothermic Reactions The system gains energy ΔH is positive N 2 (g) + O 2 (g) + 182.6 kJ
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This note was uploaded on 01/01/2012 for the course CHEM 101 taught by Professor Donahue during the Spring '11 term at Long Island U..

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04 Notes Enthalpy - Aim W hat is enthalpy QQ Draw a potential energy diagram for an endothermic reaction and label key aspects Do Now W hy do

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