Reaction Kinetics Essay

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1.0 Aim To investigate the rate of reaction of peroxydisulphate/persulphate ions, S2O82- with large scale of iodine at a number of temperatures between 5⁰C to 35⁰C and to determine the activation energy, Ea of the reaction by using the Arrhenius Equation and plotting the graph of ln time against 1/absolute temperature. The excess of iodide ions implies that the rate of reaction only depends on the concentration of the persulphate ions. 2.0 Introduction Persulphate ions, S2O82- is a very powerful oxidising agent. Some of the compounds that contain these ions are sodium persulphate Na2S2O8, potassium persulphate K2S2O8 and ammonium persulphate (NH4)2S2O8. This oxidisng agent is widely used in manufacture industry. For example, sodium persulphate is used as a bleach and detergent component whereas potassium persulphate is used as a food additive and in hair dye. The wide usage of persulphate ions makes it important to understand the properties. The persulphate compounds are solid at room temperature and has melting point above 100⁰C. They are also soluble in water. The reaction of persulphate ions with iodide ions which scientifically called the iodide clock reaction is used to investigate the chemical kinetic of the reaction. By conducting the experiment the activation energy, Ea which is the minimum energy required to start a chemical reaction can be determined. Knowing the Ea is important in order to control a system such as the temperature required for a reaction to take place within a specific time. For example, if the reaction is low, catalyst can be added to speed up the reaction. This would also help the manufacturing company to reduce the costs of operation. 3.0 Theory The purpose of the experiment is to determine the Ea of the reaction of persulphate ions with iodide ions. The equation of the reaction is shown below: S2O82-(aq) + 2 I-(aq)
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