Thermodynamics_II--Entropy (1)

# Thermodynamics_II--Entropy (1) - THERMODYNAMICS Tells...

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•Tells whether something can or cannot not happen (spontaneous) •Provides equilibrium concentrations or maximum yield •Says nothing about rate (speed)— kinetics gives rate THERMODYNAMICS Zumdahl

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EXAMPLES OF SPONTANEOUS PROCESSES •A ball rolls down a hill but never spontaneously rolls back up the hill. •If exposed to air and moisture, steel rusts spontaneously. However, the iron oxide in rust does not spontaneously change back to iron metal and oxygen gas. •A gas fills its container uniformly. It never spontaneously collects at one end of the container. •Heat flow always occurs from a hot object to a cooler one. The reverse process never occurs spontaneously. •Wood burns spontaneously in an exothermic reaction to form carbon dioxide and water, but wood is not formed when carbon dioxide and water are heated together. •Diamond is converted to graphite at 1 atm. Spontaneous processes are irreversible—without the input of energy.
TWO PARTS TO SPONTANEITY (1) H system < 0 Mcquarrie

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TWO PARTS TO SPONTANEITY (2) S system > 0 (S = ENTROPY) H 0 S > 0 What is entropy? Entropy is a measure of the amount of disorder or randomness in a system FE6 Zumdahl
SPONTANEOUS ENDOTHERMIC ( H > 0) PROCESS S > 0 Whitten

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INTRODUCTON TO ENTROPY (S) There are two types of entropy or disorder Thermal: Positional: Low T High T (In each example, the greater disorder and entropy are on the right)
GENERAL TRENDS IN ENTROPY 0. Entropy always increases when heat is added to a system.

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## This note was uploaded on 11/02/2011 for the course CHEM 126 taught by Professor Biolsi during the Spring '08 term at NJIT.

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Thermodynamics_II--Entropy (1) - THERMODYNAMICS Tells...

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