9. Why is it typically advisable (especially when using Beer's law) to make absorbance measurements at a wavelength that produces a maximum and not some other (random or otherwise different) wavelength?
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Why is it typically advisable (especially when using Beer's law) to make absorbance measurements at a wavelength that produces maximum and not some other (random or otherwise different) wavelength? [Ipt] What difference(s) would you see in the standard curve (the graph sketched below Table 1!) if a wavelength of 500nm was used for obtaining absorbance data (think about slope, y-intercept, scale, etc)? Explain. [2pt]
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QUESTION 6 What are the two reasons for measuring the absorbance of a sample at its maximum? Better sensitivity to distinguish two similar concentrations of the same chemical compound Absorbance is more accurate; the error in determining concentration will be lowest Better sensitivity to distinguish two different chemical compounds A maximum (max) is in the range of visible light QUESTION 7 The molar absorptivity of a chemical (ε) is always constant at any wavelength (ie - it would be the same at 300nm and 400nm and 500nm) True False QUESTION 8 Autozero (pressing Measure Blank) is required when a new wavelength is set True False
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The Beer-Lambert law is valid for absorbance at any wavelength (as long as the same wavelength is used for all solutions being compared). Thus, any wavelength could be used to generate a linear plot of A vs c. Why was it important in this experiment to first find the absorption maximum and use this wavelength (or one close to the maximum) for generating the Beer-Lambert plot used in these calculations? To help answer this, consider what would happen if you repeated the experiment using absorbance data at 550 nm: A. Any wavelength would work as well. B. The absorption max wavelength gives the largest slope and sensitivity. C. EDMAB only absorbs at the absorption max wavelength.
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