Chromate ion solutions are analyzed at 440 nm in a 1.00 cm polystyrene cuvette
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
Chromate ion solutions are analyzed at 440 nm in a 1.00 cm polystyrene cuvette. Absorbance values for five standards are given below.
Concentration (mol L⁻¹)
Absorbance
0.0100
0.192
0.0200
0.386
0.0300
0.575
0.0400
0.771
0.0500
0.961
(a) Using the first and last data points, calculate the numerical value and proper units of the proportionality constant relating absorbance to concentration for these measurements.
(b) A solution of unknown chromate concentration shows an absorbance of 0.648 under the same conditions. Determine the concentration of chromate in this solution, reporting the answer with appropriate units and correct significant figures.
(c) Briefly describe one limitation of using only the first and last data points to obtain the proportionality constant instead of a full best-fit analysis.