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Unformatted text preview: 1 Chemical Reaction Engineering - Musgrave Methods for Determining the Rate Law Lecture 16 - Page 1 Outline: 1. Method of Initial Rates (Fogler 5.3) 2. Method of Half-Lives (Fogler 5.4) 3. Differential Reactors (Fogler 5.5) Next Time: (Fogler 6.1-6.2) 1. Definitions (Fogler 6.1) 2. Parallel Reactions (Fogler 6.2) Chemical Reaction Engineering - Musgrave Methods for Determining the Rate Law Lecture 16 - Page 2 Differential methods require one experiment - rate data is collected at different times (although multiple experiments often used when using the method of excess). For a complicated rate law (e.g. equilibrium reactions) this approach breaks down. The method of Initial Rates requires several experiments involving measuring r A at various C A0 − r A = kC A α For example, for several values of C A0 we could plot ln − r A ( ) = ln k + α ln C A C A 0 − r A 2 Chemical Reaction Engineering - Methods for Determining the Rate Law 3 -18-18-17-16-15-14-13-12-6-5-4-3-2-1 C_A0 ln(C_A0) r_A ln(-r_A) 0.05-2.995732274-0.000005-12.20607265 0.045-3.101092789-0.00000405-12.41679368 0.04-3.218875825-0.0000032-12.65235975 0.035-3.352407217-0.00000245-12.91942253 0.03-3.506557897-0.0000018-13.22772389 0.025-3.688879454-0.00000125-13.59236701 0.02-3.912023005-8E-07-14.03865411 0.015-4.199705078-0.00000045-14.61401825 0.01-4.605170186-0.0000002-15.42494847 0.005-5.298317367-5E-08-16.81124283 − r A = kC A α = 0.002 C A 2 The following data was collected in a constant V batch reactor: ln(C A0 ) vs ln(-r A ) A nonlinear regression gives: ln(C A0 ) ln(C A0 ) ln(-r A ) ln(-r A ) − r A = kC A 2 = 0.002 C A 2 A nonlinear regression gives: − r A = kC A 2 = 0.000055 C A 2...
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This note was uploaded on 04/25/2010 for the course CHEN 4330 taught by Professor Staff during the Spring '08 term at Colorado.
- Spring '08