Chapter 3, Problem 8P

A student uses visible spectrophotometry to determine the concentration of CoCl2(aq)CoCl2(aq) in a sample solution. First the student prepares a set of CoCl2(aq)CoCl2(aq) solutions of known concentration. Then the student uses a spectrophotometer to determine the absorbance of each of the standard solutions at a wavelength of 510nm510nm and constructs a standard curve. Finally, the student determines the absorbance of the sample of unknown concentration. The original solution used to make the solutions for the standard curve was prepared by dissolving 2.60g2.60g of CoCl2CoCl2 (molar mass 130.g/mol130.g/mol) in enough water to make 100.mL100.mL of solution. What is the molar concentration of the solution? a.) 0.200M b.) 0.500M c.) 1.00M d.) 5.00M

What absorbance corresponds to 1% transmittance? To 50% transmittance?

Indicate the relationship that exists between the transmittance expressed as a percentage, T(%), and the absorbance, A.(1). A = - log [1/T(%)] (2). A + log T(%) = 2 (3). A = [log T(%)] / 100 (4). A = 100 log T(%)