Question

1. Take three cuvettes from the Containers shelf and place them onto the workbench.
2. Take an Erlenmeyer flask from the Containers shelf and place it onto the workbench.
3. There is a solution on the Materials shelf labeled 2% starch. This has a starch concentration of 1 mg/ml.
4. In the Erlenmeyer flask, you should create 100 mL of a new starch solution that is 1/400th of the stock solution using water as the filler. How much starch and water should you add? Hint: This is an application of the dilution skills you practiced in the pre-lab exercise. Use the formula from that exercise to solve this problem. Show your work in your lab notes.
5. Using the dilute starch solution from the Erlenmeyer flask on the workbench and the iodine solution found on the Materials shelf, fill the three cuvettes as follows:

Exp. 1 Cuvette Set-up
Cuvette Name	Dilute Starch Solution (mL)	Iodine (mL)
1	4	1
2	2	3
3	1	4

6. What is the final starch concentration in each of these cuvettes? Use the formula from the pre-lab exercise to solve this problem. Show your work in your lab notes. Remember to press Saves Notes.

7. Take a spectrophotometer from the Instruments shelf and place it onto the workbench. Using the control panel:

A. Select the Vis button (Vis stands for Visual) - this is a button that is selected has a gray background and blue font. The "Mode" should change from "UV" (Ultra Violet) to Vis in the view screen.

B. Set the wavelength to 620 nm:

1. Click on the number under "Wavelength" in the view screen. The present value should disappear and a flashing cursor should appear.

2. Type in 620.

3. Press Enter.

C. Confirm that the A button is selected. "A" stands for Absorbance.

8. Blank the spectrophotometer:

A. Take a cuvette from the Containers shelf and place it onto the workbench.

B. Add 5 mL of water from the Materials shelf to the cuvette.

C. Move the water cuvette into the spectrophotometer's loading well where it says "open". The digital display will show the absorbance once the lid closes. Record this ABS value in your Lab Notes. Remember to press Saves Notes.

D. Use the water as your blank solution by clicking the Zero.

E. Press the Open button on the spectrophotometer's loading well to remove the cuvette. It will automatically go back to the workbench. Discard it in the recycling bin.

9. Move cuvette 1 into the spectrophotometer's loading well. The digital display will show the absorbance once the lid closes. Record the cuvette's number, contents, and absorbance in your Lab Notes. Remember to press Saves Notes.

10. Press the Open button on the spectrophotometer's loading well to remove the cuvette. It will automatically go back to the workbench.

11. Repeat steps 9 and 10 to identify the absorbance of the remaining two cuvettes.

12. If you zoomed in on the spectrophotometer, press the Re-Set Zoom button in the lower right hand corner of the screen to go back to original view of the lab.

13. Discard the cuvettes and the Erlenmeyer flask in the recycling bin

Answer 1