The shape of the calibration curve often depends on the bandwidth That was why

The shape of the calibration curve often depends on

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The shape of the calibration curve often depends on the bandwidth. That was why the wavelength range needed to be scanned to determine the best analytical wavelength for analysis. At this wavelength, change in absorbance with concentration is at a maximum, thus yielding greater sensitivity and higher accuracy. Second, molar absorptivity is constant at this band. [3] However, Beer’s law is also subject to limitations. First, deviations become significant at higher concentrations [4] since the refractive index for the absorbed radiation is changed at high concentrations. Thus Beer’s law is ideally applicable to solutions with concentrations below 1x10 -2 M [3] that is why parts per million (ppm) is used to indicate the concentration of Cu(II). Also, Beer;s law applies to as solution that may contain more than one kind of absorbing substance provided that there is no interaction between them. [5] Chemical deviations upon dilution are also possible, leading to lesser actual concentration in some substances like the chromate ion.[2] Also, there are also instrumental limitations to consider: Stray radiation reaching the detector, sensitivity changes and power fluctuation. Fourth is when a band of wavelengths is used rather than monochromatic radiation [3] that causes the detector to measure average intensity instead of the average of the log intensities. Another source of error is the cuvette has fingerprints, affecting the transmitted radiation ang causing errors in the Absorbance. 3
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SUMMARY AND CONCLUSIONS It could be said that Absorbance is directly proportional to the Concentration of the substance by virtue of Beer’s law and was affirmed by the experiment performed using a UV-Vis Spectrophotometer. The experiment was taken to be a success given the small value of the Pooled Standard Deviation for the experiment. It was suggested that more accurate results would be obtained if a quartz cuvette was used. REFERENCES [1] Pickering, William F. 1966. Fundamental Principles of Chemical Analysis ”. Elsevier Publishing Company. [2] Klingenberg, Joseph. 1965. Introduction to Quantitative Chemistry ”. Reinhold Publishing Group [3] Pecsok, Robert, et al. 1976. Modern Method of Chemical Analysis, 2 nd edition ”. John Wiley & Sons Inc. [4] Bauman, Robert. 1962. Absorption Spectroscopy ”. John Wiley & Sons Inc.
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