Spectrophotometric study of multiple component systems in acid-base indicators



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The problem involved spectrophotometric studies of overal acid-base indicators. It tested the validity of the validity of the assumption that the ratio of the color components is the function of the hydrogen ion concentration. Spectrophotometric and potentiometric methods were combined to determine the equilibrium constants for these indicators. The optical density additivity approached ideality and the equilbrium constants obtained were in close agreement with those determined by other methods. The investigation established the validity of the optical density additivity law D = d[lowered 1] + d[lowered 2] + ....d[lowered n] applied to the two component systems studied and that the pH is a function of the ratio of the concentrations of the two colored components of the acid-base indicators through their pH ranges.