Rate Law Determination of Crystal Violet

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0.1M

Figure 5: The concentration of Crystal violet as a function of time.

[pic 6]

From this graph, we can determine whether or not the order with respect to Crystal violet is a zero order reaction, with k having a negative slope. Due to the fact that the y-intercept, in this case 0.9979, is not the closest result to 1.00, we can conclude that the order with respect to Crystal violet is not a zero order reaction.

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Figure 5: One divided by the concentration of Crystal violet as a function of time.

[pic 7]

Using this graph, we can determine whether or not the order with respect to Crystal violet is a second order reaction with k having a negative slope. Since the R2 value, 0.9856, is not the closest to 1.00, we can conclude that the order with respect to Crystal violet is not a second order reaction.

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Figure 6: The natural logarithm of the concentration of Crystal violet as a function of time.

From this graph, we can determine whether or not the order with respect to Crystal violet is a first order reaction. Due to the fact that the y-intercept (R2), in this case 0.9983, is the closest out of the calculated results to 1.00, we can conclude that the order with respect to Crystal violet is a first order reaction.[pic 8]

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Discussion:

By being taught about initial rate laws and how they affect reactions, we had a clearer understanding of why the reaction between Crystal violet and hydroxide is a first order reaction. Also, as Dr. Zegar explained, the intensity of the absorbed light is directly proportional to the concentration of the absorbing species, or put shortly, Beer’s Law.

Conclusion:

After experimentation, we used the data collected to construct a graph showing the standard curve of the absorbance of Crystal violet as a function of time and, in turn, we produced three separate graphs for the different possible orders with respect to Crystal violet at 0.1M. Then, three other graphs were created to show the different possible orders with respect to Crystal violet at 0.2M. Using the pseudo rate law method, we found that the rate law of Crystal violet and sodium hydroxide is rate=2.1*10-4 s-1[CV+]1[OH-]-1.

Error Analysis:

During our experiment, we followed the procedures to the letter and ended up only having one point in Part 1, on Figure 1, the fourth point seems to be off compared to the rest, but seeing that the R2 value is only 0.005 units away from being a nearly perfect fit, I can conclude that our data is not inaccurate.

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Bibliography:

[1] D. Paul, M. Shrethsa, and I. Zegar, Pittsburg State University,

2015.

[2] General Chemistry II Laboratory Manual, The Chemistry Department, Pittsburg State University, Spring 2017

[3] “CHEMISTRY” by J. C. Gilbert. Kirss, Foster, & Davies (4th Edt)ISBN: 9780495013341, p. 260-‐‐298.