Photosynthesis Lab Report

The majority of the experimentation in this project relied on the idea that there is a relationship between concentration and absorbance of a solution. This is easy to understand if you can visualize the particles in the solution; and this is especially true if the particles in solution portray a distinct color. The more particles there are in the solution, the more they will obstruct the path of the light. This occurs the most at the analytical wavelength, where the most light is absorbed by the particles. When light of this wavelength hits the particles, it is absorbed and there is no chance that it will reach the sensor in the spectrophotometer. However, if a solution is analyzed with a wavelength corresponding to the color of the particles,
This solution had an analytical wavelength of 380 nm, because that is the wavelength at which the complex absorbs the most light; allowing the lowest amount to reach the sensor. The source of phosphate for making our standard curve was potassium hydrogen phosphate, and this wavelength allowed us to target and analyze only the phosphate-AVM complex while yielding the least impact from the potassium ions. As for the colas, they are made with so many ingredients that it was very important to have a good analytical wavelength. In addition to phosphate, there is caffeine, sugar, corn syrup, vanilla, and many other ingredients in colas (Field); all of which could have an effect on a percent transmittance reading from the Spec 20 at a poorly selected wavelength. Using the analytical wavelength minimizes the effect that other factors in the solution have in the reading, which in turn minimizes error in the
The results of the food coloring exercise are seen in Figure 1 of the group report. The red food coloring displayed the highest percent transmittance in the long wavelengths closest to red light, which was expected. With the same logic, it was expected that the blue food coloring would have the highest percent transmittance in the higher energy wavelengths associated with blue light. In fact, the trend lines for the red and blue food coloring look almost like opposites. As for the potassium permanganate, we were interested in the wavelength that resulted in the lowest percent transmittance. This wavelength, which was 550 nm, was our analytical wavelength. This wavelength yields the most accurate results when analyzing potassium permanganate and also provides for the least error from other substances in the solution. Choosing the proper analytical wavelength for phosphate was very important for testing the colas since there are so many different ingredients that go into