Kinetics of the Decomposition of Hydrogen Peroxide in Acidic Copper Sulfate Solutions

A study on the decomposition kinetics of hydrogen peroxide in a solution of dilute sulfuric acid with added copper sulfate has been undertaken. The experiments were performed in a vacuum/Dewar flask, and the temperature of the reacting mixture was measured as a function of time. Because the decomposition was exothermic, the relationship between the temperature and time during the decomposition process was used to analyze the reaction kinetics. The decomposition reaction of hydrogen peroxide was found to be first-order, as reported by most of the previous researchers. It was found that, at an initial temperature of 67 degrees C, the decomposition of pure peroxide in dilute sulfuric acid had a rate constant of 0.0385 min(-1). The addition of 5 g of copper sulfate increased the rate constant to 0.265 min(-1), and with a further addition of copper sulfate, it asymptoted to 0.463 min(-1). It was further rather surprisingly noted that the exothermic reaction was followed by an endothermic one that did not appear to be affected by the change in the amount of copper sulfate in solution. A model was fitted to these data, and it was shown how this kinetic model can be used in practice to design an optimum batch process for copper dissolution in order to minimize the amount of hydrogen peroxide utilized.