Abstract
Experiment Technical #3 Modeling a Photochemical Smog Event: An Introduction to Reaction Rates and the Steady State Approximation Introduction Pollution levels including the presence of ozone at high levels is a major issue in today's world. There are many complicated chemical processes involved in photochemical smog events, yet can be understood by simplification The goal of this experiment is to use a model to determine reaction rates and steady state approximation, in order to understand the processes involved in photochemical smog events. Materials and Methods Three different color papers (ten each) represented three different compounds, a plastic bag represented a reaction vessel, and a die indicated probability. For experiment one, a reaction rate of 5/6 was used for the production of "B" from "A", and 1/6 for the production of "C" from "B". For experiment two, a reaction rate of 1/6 was used for the production of "B" from "A", and 5/6 for the production of "C" from "B". The data was until recorded only "C" remained and the experimental reaction rates were found. Results The modeling resulted in a graph for each experiment that only matched the fitted lines if the reaction rates were manipulated quite drastically, as seen by Figures 1 and 2.
12 10 Concentration 8 6 4
Experiment 1
A B C A Line B Line
2
0 0 20 40 60 Rolls 80 100 120
C Line
140
Figure 1. Results from Experiment 1; using k1=0.02 and k2=0.2.
12 10 Concentration 8 6 4 2 0 0 20 40 60
Experiment 2
A B
C
A Line B Line
C Line
80 Rolls
100
120
140
160
Figure 2. Results from Experiment 2; using k1=0.2 and k2=0.015.
Conclusions
Although the fitted lines closely resemble the experimental data, this is only accomplished through drastic changes in the reaction rate, and inconsistent reaction rate probabilities. However, Experiment 1 does demonstrate steady state approximation, seeing as the concentration of the intermediate ("B") was more or less steady with time. Some sources of error could include non-random rolling or choosing of papers and incorrect data recording.