Decomposing Hydrogen Peroxide Essay

1948 Words 8 Pages
Introduction The purpose of this experiment is to gain an understanding of factors which influence the rates of reactions. Several experiments will be conducted using various combinations of concentrations of the reactant (hydrogen peroxide) and a catalyst (potassium iodide), as well as one pairing in which a change in temperature is the only variable. Data collected will be used to determine the rate law, rate constant, and activation energy for each of the reactions Hydrogen peroxide (H_2 O_2) naturally decomposes into water (H_2 O) and oxygen gas (O_(2 )) according to the following balanced equation.
2 H_2 O_2 (aq) ↔ 2 H_2 O (l)+O_(2 ) (g)
Normally this reaction takes a long period of time, but the rate of reaction can be
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If the concentration of a reactant is doubled and the initial rate also doubles (21), the reaction is first order with respect to that reactant, and its exponent is 1. If the concentration of a reactant is doubled and the initial rate quadruples (22), the reaction is second order with respect to that reactant, and its exponent is 2. If the concentration of a reactant is doubled and the initial rate increases eight-fold (23), the reaction is third order with respect to that reactant, and its exponent is 3. Should the change in concentration not affect the rate, the reaction is not dependent on the concentration of that reactant, and its order and exponent are both 0 to reflect this (Chang 566-567). Because the solutions will be provided in just one concentration each, the effective doubling of reactant concentrations will actually be the result of dilutions, with the new solutions prepared using the dilution formula: M1V1 = M2V2. In one pairing of experiments, the concentration of H_2 O_2 will be doubled while that of KI will be held constant; in second pairing, the concentration of KI will be doubled and that of H_2 O_2 will be held constant. With the data obtained, the order of the reaction can be determined and represented by exponents x and y in the general rate law. Using the gas pressure probe

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