An analytical chemist calibrates a spectrophotometer for peroxovanadate at 450 nm
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
An analytical chemist calibrates a spectrophotometer for peroxovanadate at 450 nm. Using a 1.00 cm cuvette, the best-fit line for absorbance (A) versus concentration (c) is
A=(18.7±0.3)c+0.006 (c in mol L⁻¹)
Literature reports a molar absorptivity of 18.2L mol−1cm−1 for this species at the same wavelength.
(a) From the calibration results, report the experimentally determined molar absorptivity and its associated absolute uncertainty.
(b) Calculate the percent difference between the experimental value and the literature value.
(c) State whether the two values agree within the experimental uncertainty and justify your answer quantitatively.
(d) Propose two experimental factors that could account for any observed discrepancy between the experimental and literature values, explaining the effect each factor would have on the measured absorptivity.