Question

In spectrophotometry, the Beer-Lambert law relates the absorbance of a sample at a given wavelength to concentration by the following formula. a = abc You synthesize a new dve with molar absorptivity & = 2.9081 x 10+ 0.0002 x 10 M cm and use a cuvet with pathlength of 1,02 +0.03 cm. The absorbance was determined to be 0.7341 0.0009 Calculate the concentration in molarity with its associated uncertainty. (6pts) If you wanted to improve the uncertainty of your final concentration which variable would you spend money trying to improve its uncertainty? (2pts)

Answer 1

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Solution Prool of Beer -Lambest lawr @ Beer's low en 9. I is the mcident radiation of intensity and cis the concentration of the solution then, LAI XC -i) ci Lamber'ts law + If I is the mtensity of incidence wadiation 4 db is the change in the path length then Ieedb-D From equation 04@ + - 1x Cdb . => -d1=k.cdb-m nhtye K is any axbi tomy constanta Equation ID integrate it, whithin the ranges I-d I = keh b ang = ln (II/I) = kc. b e It -ě kch na of where Es Malar ab 308 fati utty I. PO whef A is the absorbance & T is a transmittana then, I A=-log, (T) = -logo (II) = -logo ( 10 € b) = EbC -> A=EBC By uring this, A 0.9341 -0.315x105 M C Eb 2.9081 X105X1-02) = 0.315x10M By using engor analysis to determine the mostainty, 44 = 4 + 4 + 46 - 8:999) + 02.034 + 340 – 9.6349x1 +0:6877 xjö€70-034 = 0.031 -4-0-031 x 0-315X10% = 9.765x10*20.009 xlo®M So, concentration = (0.315 +0.009)XiaºM If I wanted to improve the uncertainty of my final answer thes we would spend money to creare the length of cuvette. 0-03