Question

the absorption spectrum of a certain red dye is shown above. if a student analyzing the same concentration of this dye neglected to wipe fingerprints off the cuvette before placing it in the spectrophotometer, how would the absorption curve be affected?
a the peak of the curve would be higher because more light would be absorbed
b the peak of curve would be lower because less light would be absorbed
c the peak of the curve would be shifted to the left because less light would be absorbed
d the peak of the curve would be shifted to the right because more light would be absorbed.

Explanation:

Fingerprints on the cuvette would scatter light. According to the Beer - Lambert law \(A = \epsilon lc\) (where \(A\) is absorbance, \(\epsilon\) is the molar absorptivity, \(l\) is the path length, and \(c\) is the concentration), the spectrophotometer measures the amount of light absorbed by the sample. Scattered light (due to fingerprints) is interpreted as more light being absorbed by the sample (because the detector receives less transmitted light). So the absorbance values (\(y -\)axis of the absorption curve) would be higher at all wavelengths, which means the peak of the curve (which represents the maximum absorbance) would be higher.

Answer:

A. The peak of the curve would be higher because more light would be absorbed