Lecture 1 - Kinetic Theory of Gases

Lecture 1 - Kinetic Theory of Gases - Thermodynamics vs...

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Unformatted text preview: Thermodynamics vs Kinetics Chemical Reaction or Biological Process: K eq = [B]/[A] = k f /k rev (Thermo, 107A) k f = forward rate constant (Kinetics, 107B) A → B k f → k rev Thermo predicts how far a rxn proceeds (K eq ). State function depends on difference between final & initial state ( ∆ G°). Kinetics measures how fast (k f in seconds or millenia). Rate depends on barrier and details of pathway . K eq = [B]/[A] ∝ exp(- ∆ Gº/RT) k f ∝ exp(-E a /RT) C(s) diamond → C(s) coal B A Time Conc A B ∆ Gº E a A → B k f → k rev Free Energy K eq ~ 10 4 1/k f ~ 1000 yrs Glycolysis (glucose → pyruvate + NADH) Protein phosphorylation (R + ATP → R-P + ADP) Dephosphorylation (R-P + H 2 O → R + P i ) Rxn coordinate Kinetic Theory of Gases (Ch 2.6-2.9) Ch 2 Homework Problems : 52, 54, 56, 58, 62, 64, 68, 78, 98, 100 hy study gases? • Gas properties (pressure or volume) relate to speed of moving molecules (hence, kinetics). • Gas properties are easy to measure (PV = nRT). • Gas reaction kinetics modeled by molecular collisions: A → B rate ∝ (# of collisions) X (collision speed) • Kinetics of ideal gas generalize to kinetics of biological reactions in dilute solution (i.e. ideal soln: <10-3 M). Ideal Gas Properties and States Pressure (P) = Force/area (# collisions/area) Volume (V) = length* width* height Temp (T) ∝ average velocity of gas molecule n = number of gas molecules (moles) R = ideal gas constant = 8.314 J K-1 mol-1 = 0.08206 L atm K-1 mol-1 PV = nRT (Ideal gas law) Pressure V o l u m e 1 dm P = nRT V V = nRT P 1 dm 3 = 1-liter (1 L) # of gas molecules (N) in 1-liter box: moles K mol K atm L L atm RT PV n 04 . ) 298 )( 08206 . ( ) 1 )( 1 ( 1 1 = ⋅ ⋅ ⋅ = = − − molecules mole moles nN N A 22 23 10 46 . 2 1 10 022 . 6 ) 04 . ( × = ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ × = = Kinetic Theory of Gases Question: How do we describe macroscopic properties of a gas (e.g. press, vol or temp) in terms of molecular motion (i.e. speed and energy of individual molecules)?...
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This note was uploaded on 04/06/2011 for the course CHEM 107B taught by Professor Jamesames during the Winter '09 term at UC Davis.

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Lecture 1 - Kinetic Theory of Gases - Thermodynamics vs...

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