# Arise if the length of the light in the solution is

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arise if the length of the light in the solution is not directly proportional to its concentration, as the further the light is able to travel in the container, the more interactions there are with the molecules in the solution resulting in a higher absorption.[2]In contrast, a shorter travel length results in fewer interactions with the molecules in the solution and an overall lower absorption.[2]The only way to resolve this is to ensure the absorption of the solution is directly proportional to the length the light is able to travel, before starting the experiment.Summary:The KINvalues for solutions A1, A2, B1, B2 at λ1 (440 nm) were calculated to be respectively, 1.35E-4, 1.23E-4, 1.29E-4, and 1.02E-4. At λ2(590 nm), the values were respectively, 9.77E-5, 8.51E-5, 8.32E-5 and 8.32E-5. Also, solutions A3 – A6 had a linear relationship (Figure 1) between the absorbance at λ1and concentrations, meaning they were proportionately related. However, at λ2the relationship had a deviation (Figure 2), caused by a significant change in
concentration. In comparison, solutions B3 – B6 had a deviated relationship at λ1(Figure 3), alsocaused by a dramatic change in concentration, but linear at λ2(Figure 4).Learning Objectives:In the experiment, students learned how to operate a manual spectrophotometer for data analysis.Students also further strengthened their collaboration skills with others, as the experiment was divided into two parts and done in partners. Students also learned how to calculate KIN of bromophenol blue indicator, from its absorbance of light at different wavelengths and pH levels. Avoiding cross contamination with the lab equipment was also crucial to the experiment, as any contamination with the chemicals would cause significant changes in data and reduce accuracy.
References:1.CHM110H5F 2017 Course Manual; University of Toronto Mississauga: Mississauga,ON; 2017; p 66 – 692.Chemistry LibreTexts. The Beer-Lambert Law. _and_Theoretical_Chemistry/Spectroscopy/Electronic_Spectroscopy/Electronic_Spectroscopy_Basics/The_Beer-Lambert_Law (accessed Nov 21, 2017).3.PharmaXchange. Ultraviolet-Visible (UV-Vis) Spectroscopy – Limitations and Deviations of Beer-Lambert Law. -visible-uv-vis-spectroscopy-%E2%80%93-limitations-and-deviations-of-beer-lambert-law (accessed Nov 21, 2017).