Chemical Kinetics: the Iodine Clock Reaction

CHEMICAL KINETICS: THE IODINE CLOCK REACTION

D. J. SANTOS1

1INSTITUTE OF MOLECULAR BIOLOGY AND BIOTECHNOLOGY, COLLEGE OF SCIENCE

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ABSTRACT

The experiment aimed to determine the reaction order of the reaction between I- and S2O82- and observe the effects of temperature and the presence of a catalyst, CuSO4 on reaction rate. Five runs with varying volumes of 0.2M potassium iodide, 0.2M potassium chloride, 0.1M potassium persulfate, 0.1M potassium sulfate, 4mM sodium thiosulphate and fresh starch were prepared. The completion time of each reaction was measured by the indication of a blue color. Using the initial rates method and linear regression, the order of the reaction with respect to reactant S2O82- and I- was calculated. The calculated reaction order for S2O82— approximately 1 with r2 = 0.9569, and for I- was approximately 1 with r2 = 0.9985

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INTRODUCTION

Chemical kinetics is the branch of chemistry that deals with the study of rates and reaction mechanisms associated with chemical processes (Tyagi, 2006). It is an important field of study, especially in this time full of industrial processes that involve chemical reactions. For example, it allows chemists and doctors determine how quickly a new drug affects the body. Furthermore, it allows manufacturers to produce materials efficiently through the use of catalysts, or even daily processes such as spoilage of food. These are few of the many examples that illustrate the importance of chemical kinetics.

Reaction rate is defined as the change in concentration over the change in time. There are several factors that affect reaction rates: concentration of reactants, temperature, presence of a catalyst, and nature of reactants. The rate law relates the concentration of each reactant to the rate, where m and n refers to the reaction order with respect to A and B,...