Lab Report Spectrophotometry Lab

Jaspreet Singh
Professor Paratore
Biology 1
November 1, 2014
Spectrophotometry
Identifying Solutes and Determining Their Concentration
Statement of the Exercise or of the Problem
The purpose of the lab experiment was to attain the following objectives:
• Learning to Operate the Spectrophotometer
• Construct absorption spectra for cobalt chloride and chlorophyll.
Hypothesis
If greater and higher concentrations of cobalt chloride are added to each solution then greater amounts of light would be absorbed by each solution. Thus a liner relationship will result in which the absorbance of a substance would be proportional to its concentration, which will be depicted, in a linear graph.
Background Information:
The spectrophotometer is an

7) Test tube four contains 7 mL of distilled water and 3 mL of CoCl2. The fifth had 7 mL of distilled water and 3 mL of CoCl2.
8) Test tube five contains 6 mL of distilled water and 4 mL of CoCl2.
9) Test tube six contains 5 mL of distilled water and 5 mL of CoCl2.
10) After all of the test tubes are prepared, they will be put into cuvettes.
11) After you have prepared the dilutions, clean the outsides of the cuvettes with a paper towel.
12) Place the blank tube (tube 0) in the spectrophotometer. Since distilled water has no color it will not absorb any light so the absorbance number would be zero and this done to test the absorbance scale on the Spectrophotometer for the purpose of having it calibrated correctly.
13) Set the spectrometer to a wavelength of 530 nanometers.
14) Place the cuvettes (numbers 1-6) with the appropriate substance and record it’s reading in the data table.
15) After each cuvette was tested, place the distilled water sample (Cuvette zero) to reset the spectrometer and to ensure that the scale is calibrated and repeat for each cuvette test.

Data/Results:
Tube Number Concentration Of CoCL2 (Mg/ML) CoCL2 Stock (ML) Distilled Water (ML) Spectrometry Reading at

However, any doubts regarding the results may be traced to a few elements of the experiment that lend themselves to possible error. The following factors may have contributed to potential errors in the experiment; the need to zero the machine between each of the readings in obtaining the absorption spectrum and the resulting peak wavelength, the precision with which a person can accurately adjust the needle on the spectrophotometer to zero is limited, not putting in the inaccurate amount of cobalt chloride or water into the substance, and getting oil from our fingers onto the