Landolt Iodine Clock Reaction: Oxidation Of Bisulphite

This experiment was a Landolt Iodine clock reaction - Oxidation of Bisulphite by Iodate. It involved conducting three measured experiments. The first variable tested was concencentration. This was tested by conducting two experiments, each varying the concentration of either the NaHSO3 or KIO3. The varying of NaHSO3 involved using 0.1 Molar of KIO3 against decreasing concentrations of NaHSO3 (0.25 M, 0.125 M, 0.0625 M and 0.03125 M). When decreasing the concentration of KIO3, 0.25 M of NaHSO3 was used against the KIO3 (0.1 M, 0.05 M, 0.025 M, 0.0125 M). The final variable tested was temperature. A heat plate was used to test the clock reaction of 0.25 M NaHSO3 and 0.05 M KIO3 at temperatures of 30, 35 and 40 degrees celsius.
The experimental data found that as the concentration was decreased by half each time, the rate of reaction lengthened. This is keeping with Le Chatelier’s Principle. The model for the graph of concentration vs time for both NaHSO3 and KIO3 are also noted to be exponential decay functions. This shows that as the concentration and amount of reactant decreases, the time it takes to react lessens. When testing the temperature, it was found that as the temperature increased the reaction took less time to occur. This is also in line
Their experiment also tested heat using calorimetry. It was concluded that their results were linear and no reaction occured when the NaHSO3 was high. This lack of reaction can be attributed to the concentration of the NaHSO3 being too high to react with not enough KIO3 reactant to change the solutions colour. Their findings of linear results differ to our experiment as well as others. Their process involved other steps that are different to how our experiment was conducted. They also were testing for heat while we tested how temperature varied reaction rate. Their molar values were also larger than our experiment. (Kawahito, J., & Fujieda, S,