Physical Chemistry 3: — Chemical Kinetics — - Christian-Albrechts ...
Physical Chemistry 3: — Chemical Kinetics — - Christian-Albrechts ... Physical Chemistry 3: — Chemical Kinetics — - Christian-Albrechts ...
2.2 Kinetics of irreversible first-order reactions 19 I Figure 2.7: Excited-state relaxation dynamics of the adenine DNA dinucleotide after UV excitation. I Note (and warning): Anybody who wants to do least-squares fitting is urged to consult appropriate literature before doing the fitting! The book by Bevington 17 is considered required reading for any physical chemistry graduate student. As the saying goes: With three parameters, you can draw an elephant. With a fourth parameter, you can make him walk. 17 P. R. Bevington, D. K. Robinson, Data Reduction and Error Analysis for the Physical Sciences, McGraw-Hill, Boston, 1992.
2.3 Kinetics of reversible first-order reactions (relaxation processes) 20 2.3 Kinetics of reversible first-order reactions (relaxation processes) A 1 À −1 B (2.46) I Rate equation: [A] = − 1 [A] + −1 [B] (2.47) I Equilibrium at t →∞: [A] y = − [B] = − 1 [A] + −1 [B] = 0 (2.48) [B] ∞ [A] ∞ = 1 −1 = (2.49) • Therateconstantforthereversereaction −1 can be calculated from 1 and . • Or the equilibrium constant can be determined from measurements of the forward and reverse rate constants. From ,wecanthendetermineimportant thermochemical quantities, for example for reactive free radicals, via = ( B ª )( C ª ) =exp ∙− ∆ ¸ ª (2.50) ( A ª ) • Important note: — In the frequently encountered case that the number of species on the reactant and product side of a reaction differ, one has to be very careful with the units of and . Consider, for example, a gas phase reaction of the type In this case, has the dimension of mol cm 3 : B C = 1 [B] [C] = = −1 [A] 0 has the dimension of bar: A → B+C (2.51) A = 1 B C A = 0 (2.52) 0 = B C (2.53) A But the thermodynamic equilibrium constant is dimensionless: = ( ∙ B ª )( C ª ) = 0 ( A ª ) =exp − ∆ ¸ ª (2.54) ª — General relation between 0 ,and : = 0 × ¡ ª¢ −Σ ( ) = × ¡ ª¢ Σ ( ) (2.55)
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- Page 17 and 18: 1.2 Time scales for chemical reacti
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- Page 23 and 24: 1.4 References 8 2. Formal kinetics
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2.2 <strong>Kinetics</strong> of irreversible first-order reactions 19<br />
I<br />
Figure 2.7: Excited-state relaxation dynamics of the adenine DNA dinucleotide after<br />
UV excitation.<br />
I Note (and warning): Anybody who wants to do least-squares fitting is urged to<br />
consult appropriate literature before doing the fitting! The book by Bevington 17 is<br />
considered required reading for any physical chemistry graduate student.<br />
As the saying goes: With three parameters, you can draw an elephant. With a fourth<br />
parameter, you can make him walk.<br />
17 P. R. Bevington, D. K. Robinson, Data Reduction and Error Analysis for the <strong>Physical</strong> Sciences,<br />
McGraw-Hill, Boston, 1992.
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