5. To calibrate the Spectrometer, place the blank cuvette into the cuvette slot of the Spectrometer, choose Calibrate → Spectrometer from the Sensors menu. Wait for the spectrometer to warm up, then tap OK. 6. Determine the optimum wavelength for the equilibrium mixture and set up the mode of data collection. a. Empty the water from the blank cuvette. Using the solution in Beaker 1, rinse the cuvette twice with ~1 mL amounts and then fill it 3/4 full. Wipe the outside with a tissue and place the cuvette in the Spectrometer. b. Start data collection. After a moment, the absorbance vs. wavelength spectrum will be displayed. Stop the data collection. Note that the wavelength of maximum absorbance (λ max) is identified. The λ max should be 400 – 480 nm. c. Tap the Meter tab. On the Meter screen, tap Mode. Change the mode to Events with Entry. d. Enter the Name (Concentration) and Units (mol/L). Select OK.
LabQuest 10 10 - 4 Advanced Chemistry with Vernier Colorimeter Users Only 4. Connect the Colorimeter to LabQuest and choose New from the File menu. 5. Calibrate the Colorimeter. a. Place the blank in the cuvette slot of the Colorimeter and close the lid. b. Press the < or > button on the Colorimeter to select the 470 nm wavelength. c. Press the CAL button until the red LED begins to flash and then release the CAL button. d. When the LED stops flashing, the calibration is complete. e. Empty the water from the blank cuvette. Using the solution in Beaker 1, rinse the cuvette twice with ~1 mL amounts and then fill it 3/4 full. Wipe the outside with a tissue, place it in the Colorimeter, and close the lid. 6. Set up the data-collection mode. a. On the Meter screen, tap Mode. Change the mode to Events with Entry. b. Enter the Name (Concentration) and Units (mol/L). Select OK. c. Proceed directly to Step 7. Both Colorimeter and Spectrometer Users 7. Collect absorbance-concentration data for the four standard equilibrium mixtures. a. Leave the cuvette, containing the Beaker 1 mixture, in the device (Colorimeter or Spectrometer). b. Start data collection. After the absorbance reading stabilizes, tap Keep and enter the value for the concentration of FeSCN 2+ from your Pre-Lab calculations. Select OK. The absorbance and concentration values have now been saved for the first solution. c. Discard the cuvette contents as directed. Using the solution in Beaker 2, rinse the cuvette twice with ~1 mL amounts, and then fill it 3/4 full. Place the cuvette in the device, wait for the value displayed on the screen to stabilize, and tap Keep. Enter the value for the concentration of FeSCN 2+ in Beaker 2, then select OK. d. Repeat Part c of this step to measure the absorbance of the solutions in Beakers 3 and 4. Note : Wait until Step 10 to test the unknown.
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- Fall '13