Procedure

*Dearest Ms. Macke, before gasping at the horrendous 'photos,' please express foremost pity for the group who had lost most of their pictures by the effect of Alzheimer's on a digital camera. While you're at it, please take a moment to observe the rather excellent skills with Microsoft Paint  =D *
 

Part I: Measuring the Spectrum

Plug in the spectrometer and turn it on, wait 15 min for it to warm up

1. Set the wavelength knob to 600 nm
2. With the sample compartment still empty,
3.  use the zero adjust knob located on the left
4. side to reading to 0% transmittance (%T)
5. and .00 absorbance (%A).
6. Blank the machine by filling one cuvette
   with distilled water about ¾ of the way.

   

7. Insert it in the sample compartment and
    close the top.
8. Use the 100% adjust knob on the right
   hand side to set the reading to 100%T
   with the water filled cuvette holder. 
9. Adjust the T/A switch to measure the
   transmittance of the water.
10. Fill the other cuvettes with a solution of
    grape juice and water in ratios of

a)      10:0

b)      9:1

c)      8:2

d)      7:3

e)      6:4

f)        5:5

g)      4:6

h)      3:7

i)        2:8

j)        1:9

k)      0:10

9.  With a micropipette remove ¼ of the solution from the cuvettes (to prevent spillage into the machine)

   

10. Insert cuvette A into the instrument
11. and close the cover.  Record the
12. transmittance reading and the flip
13. the switch and record the absorbance
14.  reading. 
15. Remove cuvette and close the top
16. Repeat steps until all of the cuvettes
17.  have been measured.
18. Repeat whole procedure, for accuracy check.
     

Part II: Graphing the Results

1. Use the ratios with the readings from the spectrophotometer to plot a graph for the transmittance and absorbance
2. X-axis: ratios of grape juice to water; Y-axis: percent absorbance /transmittance