A student prepares five aqueous cobalt(II) nitrate standards of known concentration…
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
A student prepares five aqueous cobalt(II) nitrate standards of known concentration and measures their absorbance at 510 nm using a 1.00 cm quartz cuvette. The data are recorded in the table below.
Concentration (mol L⁻¹)
Absorbance
0.0200
0.286
0.0400
0.570
0.0600
0.854
0.0800
1.140
0.100
1.422
Answer the following questions about the relationship between the two variables.
(a) Describe the mathematical relationship you would expect between absorbance and concentration for this experiment, citing evidence from the data above.
(b) Explain why keeping both the optical path length and the wavelength of the incident light constant is critical for the validity of the relationship you identified in part (a).
(c) The slope of the best-fit line through the data is 14.2L mol−1. State the physical quantity represented by this slope and interpret its meaning in the context of this experiment.