1. A chemist determined the copper ion concentration in a batch of wine by forma
ID: 229127 • Letter: 1
Question
1. A chemist determined the copper ion concentration in a batch of wine by formation and extraction of the Cut-cuproine complex into 3-methyl-1-butanol, obtaining the data shown below. There is 1 mol Cu ion in 1 mol of Cu-cuproine complex.. (a) Convert the %T data to equivalent absorbance data and record below. Plot the A versus (wavelength) data to prepare the visible absorption spectrum for the Cut-cuproine complex in 3-methyl-1-butanol , mn %T , nm. %T 360 380 400 420 440 460 480 2.51 31.6 55.0 66.1 69.2 63.1 36.3 500 520 540 550 560 580 600 26.3 22.9 14.5 14.1 15.1 39.8 55.0 (b) Based on your spectrum, suggest the optimum analytical wavelength for the Cu-cuproine complex (c) Would distilled water be an appropriate reference solution (blank) for this analysis? Briefly explain.Explanation / Answer
1.
Absorbance = 2 - log(%T)
for the given data
(a) absorbance values would be,
wavelength (nm) A
360 1.60
360 0.50
380 0.26
400 0.18
420 0.16
440 0.20
460 0.44
480 0.58
500 0.64
520 0.84
540 0.85
560 0.82
580 0.40
600 0.26
(b) The optimum wavelength for the experiment would be at 540 nm, which gives maximum absorbance value.
(c) 3-methyl-1-butanol would be an appropriate blank for the experiment as it is used as a solvent here. Water would not be an ideal blank.
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