Answer both questions, i) - ii). (0.5 marks each) The UV-visible spectrum of a c
ID: 1022456 • Letter: A
Question
Answer both questions, i) - ii). (0.5 marks each)
The UV-visible spectrum of a cobalt complex-containing solution was measured using a spectrophotometer, with all measurements taken in a standard cuvette (l = 1cm). The solution was repeatedly diluted a dozen times, and all 12 spectra are shown together below. The dotted line represents the original undiluted spectrum.
i) If the original concentration of the solution was 0.050 mol L-1, determine the concentration of the most diluted solution.
ii) Determine the molar extinction coefficient, ?, for this material at ?max = 261 nm, using the Beer-Lambert Law, A = ?cl.
a) 0.050 mol L-1 b) 0.019 mol L-1 c) 0.029 mol L-1 d) 0.086 mol L-1Explanation / Answer
a) the most diluted solution will be 0.019 mol / L
b) according to Beer Lamberts law
A = cl
Absorbance is nearly 0.8
0.85 = X 0.05 X 1
= 1.7 X 10^1 L mol-1 cm-1
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