Chem 218 Exp 2

# Determining maximum absorption ? max wavelength t for

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Determining maximum absorption (λ max) Wavelength %T for #5 A 410 72 0.142668 430 88 0.055517 450 93 0.031517 470 93 0.031517 490 95 0.022276 510 94 0.026872 530 96 0.017729 550 91 0.040959 570 99 0.004365 590 93 0.031517 610 95 0.022276 Readings at λmax Standard Solution %T A #1 60 0.221849 #2 58 0.236572 #3 68 0.167491 #4 75 0.124939

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#5 91 0.040959 Unknown 67 0.173925 Observations: All solutions except the pure ASA were purple colored and as the concentration rose the solution became darker purple. Calculations A = -log T =-log(0.93) = 0.031517 M1V1=M2V2 Stock Solution A: (1M) (0.25L) = M2 (0.050L) M2 = 0.04M Concentration of SA in volumetric flask A (0.29g/138.12g/mol)/250 mL x100=0.000839849 mol/L Concentration of SA in volumetric flask B (0.000839849 mol/L) x 0.050L = 0.000041992 mol/.250L = 0.00016797mol/L Results and Discussion In part one, we found that all the ASA dissolved addition of extra water was not necessary to complete the solution It also took very little time for the solution to cool to room temperature after heating. In part three, we found that the solution turned a purple color when adding Stock Solution B to the FeCl 3 solution. The less of the solution we added, the lighter purple the solution was, allowing more light to pass through the solution. The unknown and the known solutions that were most similar in mass percent were the same shade of purple. Also, before converting solution A to solution B, the flask had to be inverted several times to ensure that there was a homogenous mixture, because when just adding deionized water, the solvent may just settle at the bottom.
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• Fall '12
• professoridon'tknow
• Salicylic acid, standard solution

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