A student analyzes an aqueous solution of cobalt(II) nitrate at its wavelength of…
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
A student analyzes an aqueous solution of cobalt(II) nitrate at its wavelength of maximum absorbance.
The spectrophotometer uses a disposable cuvette whose stated path length is 10.0mm, but the manufacturer’s certificate indicates that the actual path length for this batch is 15.0mm. The student records an absorbance reading of 0.433 at the selected wavelength. At this wavelength, the molar absorptivity of Co(II) is 5.15×102L mol−1cm−1.
Use the information provided to answer the following questions.
(a) Convert the certified path length of the cuvette from millimeters to centimeters.
(b) Using the converted path length, determine the molar concentration of Co(II) in the sample. Show all steps and include appropriate units.
(c) Report the final concentration with the correct number of significant figures and in scientific notation.