Spectronic 20

This paper utilizes the Spectronic 20 to optically determine the kinetics of the reaction between bromocresol green (designated HBCG) and bleach (designated ClO–) as a function of concentration and temperature. The technique uses a crossover or intersection time, tx, of the percent transmission (%T) for the reaction and the predetermined percent transmission of a standard solution. This technique requires less data to be collected than other techniques thereby reducing the laboratory time for each experiment. The reciprocal of the crossover time for a first-order reaction is proportional to the rate and rate constant of the reaction. These results agreed rather favorably with the reported conventional visual-color-matching techniques. The reliability of the optical technique can be greatly enhanced by better controlling the experimental conditions for temperature fluctuations, mixing, and cuvette transfer rates.