A mathematical analysis of the titration data for the ideal polymer containing a periodically repeating functional group capable of reversibly attaching ligands in solution was performed. The titration curves were described by applying a matrix method to calculate the equilibrium constant of polymer complex formation. The results of mathematical modeling were compared with experimental data. On this basis, the concentration dependence of the equilibrium constant for the deprotonation of a synthetic poly(ribouridylic acid) in aqueous solution was proposed.