Chem 112 Exam 1

Chem 112 Exam 1 - o If more than one orientation, use:...

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Chem 112 Exam 1 Enthalpy: o T changes o q=∆H=C∆T ∆H (+) = endothermic ∆H (-) = exothermic Phase Change o Constant T o Solid →fusion→ Liquid →vaporization→ Gas (endothermic) o Gas →condensation→ Liquid →freezing→ Solid (exothermic) Chemical Reaction o Assume 25˚C o ∆H=∑n∆H f ˚ (products) - ∑n∆H f ˚ (reactants) Entropy: Randomness, disorder, chaos ∆S universe > 0 for spontaneous/thermodynamically favored processes Special Case: o Crystals @ 0 Kelvin (NO motion/thermal disorder) o Only possible disorder is positional o If only one possible orientation, there is no disorder; S=0 “perfect”
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Unformatted text preview: o If more than one orientation, use: S=klnW where: k = constant = 1.381x10-23 J/K W = z n = # of orientations # of molecules • Heating & Cooling o ∆S=ClnT f /T i • Phase Change o ∆S=q rev /T ; ∆S=∆H/T • S m ˚ & chemical structure o Phase S gas >> S liquid > S solid o Molecular complexity S complex > S simple o Mass S heavier > S lighter System & Surroundings • ∆S universe =∆S system + ∆S surrounding • ∆S system =∆S reaction • ∆S surroundings =-∆H system /T...
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This note was uploaded on 04/29/2008 for the course CHEM 112 taught by Professor Sheffield during the Spring '08 term at Allegheny.

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