# Analysis Of The Beer-Lambert Law

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Register to read the introduction… The results obtain from the experiment did fit to an extent the
Beer-Lambert Law, there where two point that where close to the doubling effect that is described by the Beer-Lambert Law but not quite. This can be accounted to a possible pipetting error. Once all of the liquids that are to be use are in the test tube you will vortex each tube before placing the in the spectrophotometry, making note of the color. Since the vortex aid the sample to actually mix completely we take note of any color change that might show more deprotonating of the sample. During the second part of the experiment when we took a sample to construct our absorbance spectrum the spectrophotometry machine would not zero out, hence instead of beginning from zero, we began from a whole number like .600 and subtracted the results of the absorbance by this.

Experimental results:
The wavelength of the absorbance peak found was at 400nm which is fairly close to the standard λ that was used to conduct the experiment of 405nm. It was also noted the PNP solution changed form a clear solute at pH of 4 to a yellow solute at pH of
10.
Data Collected:
Worksheet #1
Test
tube
Number
1
2
3
The source of experimental error is more sytematic than gross for the data collected as only one of the points its outside the line. The concentration of the PNP obtain for the unknonw #85 was 0.029 ±.001 (µmoles/ml). This was obtain from using the PNP standard curve obtain from results of test tube 2-11. Once we identify the absorbance attain in our test tube #12-19, they were plotted against the standard curve and we are ablie to obtain the amount of PNP in the tube in µmoles. Once we had the amount we could rearrange the equation we used for acquiring the amount of PNP previously. This

gave us the concentration of the unknown, and then we took all the average of all the concentrations to the unknown’s actual concentration. The data was consistent as it was only observe one result to vary more than .003 from the actual number. The calculation of the extinction coefficient of P-Nitrophenol for the experiment was 1.53 x 104 M-1•cm-1, this compare to a fellow student (Sean Clark-Garvey) who had a result of 1.67 x 104 M-1•cm-1 seem to be close to each

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