Project 13- Analysis of Colas

001m kmno4 from 625ml of a 0004m sample this solution

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Unformatted text preview: different color solutions and various compounds have different absorbencies and transmittance percentages. Transmittance and absorbency are inversely related. Also, at a solution’s analytical wavelength the more concentrated a substance the more absorbency it has as a solution and therefore the lower the percent transmittance. By determining the analytical wavelength a substances properties can be more accurately determined, such as absorbency, transmittance, and concentration. By calculating a calibration curve for a given substance, you can determine a concentration of a solution by 8 looking up the absorbance of that given solution. Beer’s law was enforced as a result of this and showed that this model can still make predictions. Experimental Section Calibrating the Spec 20 Beginning with the first part of the lab, the Spectronic 20 was first needed to be understood and calibrated. The Spec 20 was turned on and left alone to warm up for ten to twenty minutes during lab preparation. After being left alone for some time the Spec 20 was calibrated by inserting a blank (usually water) in the slot. Then the right knob was turned so that the pin was pointing directly at 100. Then the blank was taken out and the left knob was turned to 0. After this was done the machine is now calibrated. Preparation of Food Coloring Solutions and KMnO4 One drop of red food coloring was added to 50mL of water and stirred until evenly colored. The same thing was repeated for the blue food coloring solution. The third solution was made by combining 25mL of both blue and red solutions to make 50mL of a mixed solution (purple in this case). These solutions were mixed again and set aside. Next for the last solution, the dilution equation was used (m1v1=m2v2) to create a 25ml sample of 0.001M KMNO4 from 6.25ml of a 0.004M sample. This solution was then placed aside. Measuring the Percent Transmittance of the Four Solutions Next the Spec 20 was calibrated with water as a blank. Samples of the four solutions were then poured into four clean crystal cuvettes and then entered into the Spec 20. All four solutions’ percent transmittance was measured from wavelengths 350 ­650 (nm). After each wavelength for the solutions were measured the device was recalibrated for optimal accuracy. The data was recorded and graphed in Microsoft Excel. Preparing and Measuring the Diluted Solutions of KMNO4 Beginning with 0.004M of KMNO4, the dilution equation was used to prepare 0.001M in a 25mL from 6.25mL of the beginning sample. This sample was then placed into a crystal cuvette then entered into the calibrated Spec 20. The results were then measured, and recorded at the analytical wavelength 530. Next from the 0.001M solution the equation was used again to prepare 0.0001M (25mL) from 2.5mL of 0.001M. This sample was placed into a cuvette and percent transmittance was measured at the analytical wavelength. Then the 0.0001M solution was diluted to 0.00015M and created 10mL. This 0.00015M solution was then entered into the Spec 20 and measured at th...
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