This applet models the Rice-Herzfeld mechanism for the kinetics of the chain reaction CH3CHO (g) ⇒ CH4 (g) + CO (g). The four rate constants are defined for the four steps of the mechanism, as shown in the box on the left hand side of the applet.
Solution of the overall rate equation for the reaction yields a reaction order of three-halves, in agreement with experiment. However, the mechanism does not fully account for all the by-products of the reaction.
This applet models the chain reaction stochastically, by comparing a new, randomly generated number with the rate constant each small time interval. When the random number is less than the rate constant multiplied by the time interval, the event occurs. Because of the stochastic nature of the simulation, there is no need to prostulate the steady-state approximation; in fact, the concentration of intermediate A . (acetyl radical) can be observed over the course of time, to verify how well the approximation holds (or doesn't).
Click on the appropriate button below to increase/decrease the concentration of A ([A], acetaldehyde), or any of the four rate constants k1, k2, k3, or k4.
© 2003-2011 by Lawrence T. Sein. All rights reserved.
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