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Irreversible Uncatalyzed Reactions
2nd Order (2 Reactants-1 Product)
Description | Equations | Implementation | Examples | Discussion
Examples
Limiting Reactant To run this model, click on the following parameter file, example1.par. This simulation will allow you to change the initial concentrations of the two reactants, S1 and S2, and to observe the resulting production of product, P1. Once the model and the parameter files load, open "Plot_Area 1". Then run the model.
What final concentration of product is produced? Now vary the initial concentration of S1 between 55 and 100 mM without changing the concentration of S2, and rerun the simulation noting the concentration of product produced in each case. Two or three concentrations of S1 should show you sufficient data to discern a pattern. Does the amount of product produced vary when altering the concentration of S1 as instructed above?
What happens to the concentration of product produced when the initial concentration of S1 is set to 40 mM while the initial concentration of S2 remains at 50 mM? Reduce the initial concentration of S1 to 25 mM and rerun the simulation.
By now, you should have noticed that the concentration of product formed never exceeds the initial concentration of the reactant with the lowest initial concentration. The reactant in lowest concentration is known as a "limiting reactant".
Total System Concentration
Before we run the simulation again, ask yourself what the total concentration of components in the system (S1, S2 and P1) would be throughout the time of the simulation given the nature of the chemical reaction modeled? Now change the initial concentration of S1 back to 100 mM, and rerun the simulation. Activate the line in "Plot_Area 1" which plots "S1+S2+P1". Did your prediction match the result obtained? Remember that the total number of molecules does not remain constant during the chemical reaction; two reactant molecules combine to produce only one product molecule.
4-2-1-6-1.
Contact John Bassett for comments or questions.
Copyright © 2002 NSR, University of Washington. All rights reserved
Revised 04/22/02