CHEMISTRY LAB REPORT : KINETICS

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Introduction. Kinetics is the study of the rates of chemical reactions. In this experiment you will be studying the rate of the redox reaction between the arsenic acid and the iodide ion in aqueous ... solution. You will investigate how the rate changes when you vary the concentration of the reactants and also when you vary the temperature. You will use these experimental measurements to determine the rate law and to calculate the activation energy for the reaction. You can read about the basic ideas of kinetics- including rate laws, rate constants, mechanisms, and activation energy- in the Kinetics chapter of your textbook. The Reaction. The iodine clock reaction refers to reactions that change color from colorless to a blue color due to the formation of the triiodide ion combining with starch. This change in color come in very exact timing. The iodine clock reaction that you will be studying is the following: 6 H+(aq) + IO3-(aq) + 8 I-(aq) -> 3 I3-(aq) + 3 H2O(l) (RXN #1) To better be able to study the timing of this reaction we add a reducing agent, arsenious acid which reacts rapidly with the triiodide ion as shown in RXN 2 below, and thus delaying the blue color. Once all the arsenious acid is reacted then the color changes to blue due to the triiodide-starch complex. H3AsO3(aq) + I3-(aq) + H2O(l)  HAsO42-(aq) + 3 I-(aq) + 4 H+(aq) (RXN #2) [Show More]

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