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Calculate k using a spreadsheet and following these steps:

1. Because denitrification follows a 1st order reaction rate, plot time versus In of the

concentration.

2. After plotting the values, calculate the slope of the resulting line through 3 different

methods:

a. Choose any two points to estimate the slope (Ay/Ax)

b. Calculate the slope between each consecutive point value. For example, calculate

the slope between day 1 and 6, 6 and 10, 10 and 14 and so on. Then calculate the

mean from all the slopes obtained

c. Use MS Excel to calculate the best linear fit and equation form the resulting plot.

Get the slope of the best fit line from the resulting equation. This slope will be

your third k value.

3. Compare all k values obtained and choose the best value.

Report: Please prepare a lab report showing how you estimated k. Under a section called

methods, explain the rationale of all the methods used to calculate k and which method(s) is the

best one to determine k and why. Show the calculations done to estimate k using all the methods

described above. Explain what is the final denitrification rate coefficient that you have decided to

use. Provide a short discussion on how you estimated the final k value. Include some

conclusions on this discussion. You can write the report individually or in groups of 2 or 3

students. Report is due on Wednesday, October 18 at the beginning of class.

Fig: 1