Thermodynamics2

# Thermodynamics2 - T h e rm o d y n a m ics - E n th a lp y...

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Page ‹#› ! Spontaneous processes: Processes that occur without intervention. ! Examples: 1. Ball rolls downhill. 2. Heat flows from a warmer object to a colder object. 3. Wood burns to form CO 2 and H 2 O. Thermodynamics - Enthalpy ! Exothermic reactions release energy as stronger bonds are formed. ! Exothermic reactions have ! H < 0. ! You might expect exothermic reactions to be more spontaneous than endothermic reactions. Thermodynamics - Enthalpy ! Spontaneous Reactions:Always ! H<0 ? Water(ice) spontaneously melts when placed on the table at room T. ( ! H>0) Must be something else ?? What about randomness ?? Thermodynamics - Enthalpy Thermodynamics - Probability ! Consider a molecule, A. What is the probability of all the molecules being in the LEFT bulb? ANSWER: 1/2 ! What is the probability of all the molecules being in the LEFT bulb? ANSWER: 1/2x 1/2 = 1/4 or (1/2) 2 Thermodynamics - Probability ! Number of Relative molecules probability 1 1/2 2 (1/2) 2 3 (1/2) 3 10 (1/2) 10 n (1/2) n Thermodynamics - Probability

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Page ‹#› ! Nature tends to move spontaneously from a state of lower probability to one of higher probability. ! Nature tends to move spontaneously from more ordered to more random states. Thermodynamics - Entropy ! Entropy - A measure of the disorder or randomness of a system ! 2nd Law of Thermodynamics - For spontaneous processes, the Entropy of the Universe increases. ! Suniv=
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## This note was uploaded on 12/25/2009 for the course CHEM 201 taught by Professor Warren during the Spring '09 term at N.C. State.

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Thermodynamics2 - T h e rm o d y n a m ics - E n th a lp y...

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