The dye rose bengal (RB) or Eosine Y react with Cl2 produced by electrolysis at Pt. electrode (in presence of KCl). To determine the order of the reaction the absorbance of the dye is plotted vs time of electrolysis. The curve A vs time shows unexpected behavior, there is increase in the first 40 s then decreases linearly. My question: Why the absorbance of the dye increases since A is proportional to the concentration of the dye and there is theoretically decrease in the dye concentration (chemical reaction with Cl2). no addition of Cl2 on the aromatic ring since no shift in the wavelength max and no isosbestic point.