Lab Report

The purpose should include a majority of the topics and techniques covered in the experiment. The procedure section should cite the lab manual and include any changes made to the procedure during lab work.

The data section should include the following completed table:

Run Number	[ KI] (M)	[Na₂S₂O₃] (M)	[(NH₄)₂S₂O₈] (M)	Time (sec)	Rate of Reaction (M/sec)	Temp. (K)	K (determine units)
1
2
3
4
5
6
7
8

To determine the [KI], determine the number of moles in the volume of KI you are using in each trial and divide that amount by the total volume for each run. (Hint: 20 drops = 1 mL). Repeat these calculations to determine the [Na₂S₂O₃] and [(NH₄)₂S₂O₈]. To calculate the rate of the reaction divide the [Na₂S₂O₃] by the time.

Next, to determine K, you must fill in the table below and make two graphs.

Run Number	log[KI] (M)	log[(NH₄)₂S₂O₈] (M)	log Rate of Reaction (M/sec)
1
2
3
4
5
6
7
8

One graph will have the log of the rate on the y- axis and the log of [KI] on the x-axis only using runs 1-3, the slope of this graph will give the value of m in the following equation:

To find the value of n you will do the same thing but this time instead of graphing the log of [KI] graph the log of [(NH₄)₂S₂O₈] and runs 1, 4-5 only. Now that you have m and n you can plug the rate, and [KI] and [(NH₄)₂S₂O₈] into the rate equation:

and solve for K for each of the eight runs. The units for K depend on the values of m and n, be sure you have the correct units. Also be sure to include the values for m and n, both values should be whole numbers so do not forget to round.

Finally report the E_a and A, the activation energy and frequency factor for this reaction. To do this prepare a graph of ln(K) vs 1/T for trials 1,6 and 7. The slope of this graph is equal to –E_a/R and the y-intercept is ln(A). Take note: You are now using the natural logarithm, Ln.

In the calculation section include the three graphs explained above. All graphing guidelines apply. Also include sample calculations for the following: [KI], [Na₂S₂O₃], [(NH₄)₂S₂O₈], rate, K, E_a and A.

The conclusion section should be several paragraphs containing all of the values obtained, be sure to include the rate equation. This section should also include a comparison of the rate constants at the same temperature. A well developed discussion of the rate constants for all runs, including both similarities and differences. Also an explanation of the value for E_a . Lastly discuss the accuracy and errors in this experiment.

Answer the following questions:

You were introduced to "Kinetic Molecular Theory" (KMT) in Chm1045 and recently reviewed the concept in CHM1046. Use KMT to explain how temperature affects the rates of chemical reactions. Be detailed in your explanation.