THEORY OF CURVED MOLAR RATIO PLOTS AND A NEW LINEAR PLOTTING METHOD

By Introducing an idea of “normalized absorbance” into the familiar molar ratio method, theoretical general equations are shown to describe curved plots encountered with weak complex systems. “Normalized absorbance” means the degree of complex formation, but may also be called the degree of undissocia-tion, as opposed to the degree of dissociation. At the same time, “the effective concentration factor of ligand used” is introduced for practical use of the method, as if formally corresponding to activity coefficient. Several important features of the curved plots are examined qualitatively, and a new linear plotting method is used to obtain quantitative information. Experimental data and applications of the new technique are discussed. The discussion suggests that the purities of ligand reagents are important in complex formation studies. © 1969, American Chemical Society. All rights reserved.