Kinetics of the Traffic Light Reaction
Kinetics of the Traffic Light Reaction
Jihyun Yoo
Measuring the Stoplight Reaction Kinetics
Times of Traffic Light Reaction Color Change
Plot the absorbance (Abs) vs. time for the green, red, and yellow kinetics on one graph. Be sure to include a legend and axes labels.
What time in your Absorbance vs. Time spectra will you use for determining the kinetics of the first reduction (green to red, 760 nm) and the second reduction (red to yellow, 553nm)?
(a) First reduction: 0 ~ 15 seconds
(b) Second reduction: 15 ~ 66 seconds
Determining the Kinetics of the Traffic Light Reaction
The linear equation and R^2 values for the disappearance of green IC
Absorbance vs Time
In (Absorbance) vs Time
1/Absorbance vs Time
Based on these graphs, determine the reaction order with resect to indigo carmine (IC)
The reaction is zeroth order because R^2 value of the absorbance is closest to 1
Determine the rate constant k' with correct units from the simplified rate law for the first reduction, where rate = k' [IC]^m
K' = -slope = -(-0.06027 m/s = 0.0602 m/s)
Rewrite the final rate law for the first reduction of IC with your rate constant and reaction order
rate = 0.0602 m/s [IC-H]
Linear equation and R^2 values for the disappearance of red IC-H
Absorbance vs Time
1/absorbance vs Time
In (absorbance) vs Time
Based on these graphs, determine the reaction order with respect to IC-H (red to yellow)
The reaction is zeroth order since R^2 value is closest to 1
Determine the rate constant k' with correct units from the simplified rate law for the second reduction, where rat = k' [IC-H]^p
rate = k' [IC-H]^p = - slope = -(-0.0602) m/s = 0.0602 m/s
Rewrite the rate law for the second reduction of IC with your rate constant and reaction order
rate = (0.0602) m/s [ZC-H]^0
Beyond the Lab Bench
1. You measured the absorbance of the yellow IC-H2 product at 424 nm but did not use this data for identifying the reaction order and rate constant. What was the purpose of collecting this data?
Based on the experiment, yellow was a basic color before its changes to red and green. Therefore, measuring the yellow value helps me identifying when the color starts to transit to red and then green. Moreover, it can also provide precise graphs of kinetic reaction.
2. In 2-3 sentences, briefly explain the role of temperature in this lab
The role of temperature is really critical to the rate constant. Depends on the temperature, the reaction can be fast or slow. Based on what I did on the experiment, as I shake the cuvettes, inside particles made heat which changes color in faster rate so, I can conclude that high temperature makes reaction occurs much faster than low temperature does.
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