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CHEMICAL KINETICS: THE IODINE CLOCK REACTION

DARLENE M. ROXAS

NATIONAL INSTITUTE OF MOLECULAR BIOLOGY AND BIOTECHNOLOGY, COLLEGE OF SCIENCE

UNIVERSITY OF THE PHILIPPINES, DILIMAN, QUEZON CITY 1101, PHILIPPINES

DATE SUBMITTED: 10 DECEMBER 2013

DATE PERFORMED: 23 NOVEMBER 2013

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ABSTRACT

In a given chemical reaction, the reaction rates are expressed and explained through chemical kinetics. The iodine-clock reaction aims to explain concepts of reaction rate and show the effects of major factors in the reaction rates including the concentration, temperature and presence of catalyst between persulfate and iodide ion. Five different runs with different concentrations of S2O82- and I- were prepared to find the reaction order of each reactant using the initial rate methods and graphical methods. The rate law established base from the experimental data was R=k[S2O82-][I-]. Other sets of run with constant concentration were prepared under different temperature condition: cold (50C), room temperature (29oC), and hot (50oC) and the calculated activation energy (Ea) and Arrhenius constant (A) was 5.043 x104 J/mol and 1.639 x1010, respectively, using the Arrhenius equation. A set with constant concentration and constant temperature was prepared and treated with CuSO4 to test the effect of catalyst to the reaction rate. The change in concentration, temperature and presence of catalyst showed a significant change in the reaction rates of persulfate and iodide ion. Faulty timer and disturbed nature of solutions due to physical factors are the possible reasons of errors in the data.

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INTRODUCTION

Chemical kinetics is the study of reaction rates, the changes in concentrations of reactants (or products) as a function of time [1] and can be described using the formula (1) given in this hypothetical reaction

aA bB.

(1)

Many of...