Need help with a lab question about UV Spectrocopy. I need a small disscussion a

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Need help with a lab question about UV Spectrocopy. I need a small disscussion about the advantages and disadvantages that are apparent to you when performing this type of measurement.   

C Chegg Study Guided C Need Help With A Lab C Microsoft Word UV-vis x Microsoft Word pKa l Part 2 The flexibility of UV-Vis spectrophotometer can be expanded beyond the scope of a single analyte in a given sample as long as the absorbing species do not interact or react chemically with one another. When the solution containing two or more species interacts with EMR at a given wavelength. the total absorbance is additive of absorbance for individual component. That is to say, the total absorbance of a mixture is the sum of the absorbances, which the individual components would have at a given wavelength. Recall that for a single component, x. Beers Law states: A.- EDC, where E is the molar absorptivity, bis the path length and Cr is the molar concentration of species, x. If we use the same cuvette for each sample, the path length is constant. and the two constants 8 and b can be combined into a single absorptivity constant, k. Therefore: A AC This k represents the proportionality constant between A and Cr for component x. Look farniliar? This is the slope of the calibration curve or the sensitivity Remember the molar absorptivity s dependent upon wavelength. so is k. So, this sensitivity (k) is only good for one length. If we have a two component system, x and y, we can expand this total absorbance as: where RA- and ka-lay are the absorptivity constants for components x and y at a given wavelength. AR-u. If we measure the absorbance at a second wavelength, Aa-2, we can obtain: Note: the absorptivity constants have changed for this new wavelength We can determine the absorptivity constants for each component by making a calibration curve at two different wavelengths for each component- This leaves us with 2 unknowns, Cr and Cy, and 2 equations. We ather soluti In part 2 you will examine the use of this procedure in the analysis of a mixture of 2 of the anesthetics. p-cresol and resorcinol. These two anesthetics have maximum absorbances at 277.0 nm and 2733 nm for p cresol and resorcinol. respectively. Your system of equations you will have to solve will be here kansanmd,kzNA ovar, kam and A. oen are obtained from calibration curves of those respective standards and at both 273.3 and 277.0nm opes of calibration curves) Talk or type to search 2-27 PM /31/2017

Explanation / Answer

UV-Vis analysis

A particular sample or compound absorbs at a particular wavlelength referred to as lambda max.

When another solute is added to the mixture, the value for lambda max might get a bit shifted depending upon the interaction of the added compound with the already present compound in the solution.

The resultant absorbance will be the added absorbance from the contribution from both the components (when only two are present). This can be extended to mixture with more than two components easily and to measure absorbance of such systems. the method is very usedful in determining the concentrations of components in a mixture and give good results when taken in multiple readings.

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