Ch9 Worksheet thermo

# Ch9 Worksheet thermo - CH101/Ison Name: _, _ Ch9...

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CH101/Ison Name: ___________, __________ Ch9 Thermodynamics I. Energy : Energy is constantly exchanged between the system and the surroundings, where… E universe = E system + E surroundings = 0 E system = - E surroundings 1. If the system gives off energy, what do the surroundings do with that energy? II. Heat and work: Heat (q) and work (w) are the most common ways to exchange energy between the system and surroundings. E system = q + w (+) q: heat is absorbed by the system: ENDOTHERMIC (-) q: heat is released by the system: EXOTHERMIC (+) w: work is done on the system (-) w: work is done by the system Practice problems: 1. If we assume that a hot pack is the system, what is the sign of q? _________ 2. What is the energy change of a system that absorbs 500J of heat and does 300J of work? _________________ III. Enthalpy or heat of reaction ( H): The heat transferred in a chemical reaction (constant P) is the enthalpy or heat of reaction, H Energy Reaction coordinate Reaction coordinate EXOTHERMIC ENDOTHERMIC EXOTHERMIC ( - H) ENDOTHERMIC (+ H) Practice problems: 1. What is the sign of Δ H o for the evaporation of water? ____________ 2. What is the sign of Δ H o for the cooling of liquid water? ___________ IV. Properties of Δ H o : 1) Δ H o is proportional to n (# of moles of reactants and products) 4Fe(s) + 3O 2 (g) Æ 2Fe 2

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## This note was uploaded on 09/17/2009 for the course CH 101 taught by Professor Bigham during the Spring '08 term at N.C. State.

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Ch9 Worksheet thermo - CH101/Ison Name: _, _ Ch9...

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