14. To determine the order for CV+,compare the values of the correlation factors for each graph. The graph that produces a correlation factor that is closest to the value 1 defines which of the three graphs produces the best fit line. To select the correct graph tap the y axis and from the drop down list select the correct label,absorbance, lnA or 1/A based on your correlation factor. 15. To determine the average (mean) temperature during the course of the reaction for this graph go to the Graph Menu and select Graph 2 (see step 7). You should see a plot of temperature on the y-axis vs.time on the x-axis. Highlight most of the graph with the stylus, then from the Analyze Menu select Statistics, tap the box next to Temperature and record the mean temperature, Tmean, in your lab notebook.
7 PART B 16. Your instructor will divide the class into 5 Groups (1 5). Each group, consisting of a two pair of students, Team A and B, which will be assign a specific temperature range to run the reaction. Data will be shared between groups to complete the second table in the data sheet. The breakdown of assignments will be as follows: Bench 1 Group “1”Each pair of students will do two trials in the 5 - 10°C range –use ice and water Bench 2 Group “2”Each pair of students will do two trials in the 15 - 20°C range –use ice and water Bench 3 Group “3”Each pair of students will do two trials in the 25 - 30°C range –use digital hot plate Bench 4 Group “4”Each pair of students will do two trials in the 35 - 40°C range –use digital hot plate Bench 5 Group “5”Each pair of students will do two trials in the 45 - 50°C range –use digital hot plate Shallow aluminum pans will be used for the hot plates while plastic containers will serve as ice/water baths. 17. Use the burets to dispense 10.00 mL of the CV+solution into a 30 mL beaker and 10.00 mL of the sodium hydroxide solution into another 30 mL beaker. Place them both in the ice/water bath, and make sure that no water splashes into the solutions. Use an alcohol thermometer to monitor the temperature of your water bath. 18. Measure the temperature of the CV+solution and the sodium hydroxide solutions using your temperature probe. Be sure to wipe the temperature probe dry before placing it in another solution so as to avoid contaminating the solutions. The temperatures should be the same. 19. Re-check the following settings (in upper right of the screen): Mode: Time Based Rate: 360 samples/min Length: 2 min Before starting a new Run, you should tap the file cabinet icon (next to the box that reads Run 1) with the stylus. This will create a new graph for Run 2. Instructions for Groups 1 - 4 20. When the temperature of both solutions are the same and close to your assigned temperature, pour the contents of NaOH beaker into the CV beaker and stir the mixture for about 5 secondsusing the temperature probe. Leave the mixture in the water bath. Fill the cuvet about ¾ with the reaction mixture. At the same
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