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Unformatted text preview: Determination of Rate Law and Activation Energy March 4, 2006 Introduction The purpose of the experiment was to determine the rate law, half-life, and activation energy for the reaction of crystal violet and sodium hydroxide. The rate law can be determined by finding the order of the reaction and the reactants. The general rate law for the reaction is Rate = K[CV + ] n [OH- ] p . N and P represent the reaction order. A rate law shows how the rate of a reaction depends on the concentration of the reactants. K is basically the proportionality constant of products over reactants. This usually called the differential rate law. The integrated rate law, however, shows how the concentrations of the reactants depend on time. A first order reaction would be a reaction that is only dependent on the concentration of the reactions to the first power. This type of reaction would have a linear line when graphed. The integrated rate law to draw a straight-line plot for a first order reaction is ln[A] = -kt + ln[A] o . A second order reaction would be a reaction that has a reaction order of two. For example, if the concentration of one reactant is doubled, then the reaction rate quadruples. The straight line plot for this reaction would be 1/[A] = kt + 1/[A] o . The half-life of a substance is defined as the amount of time that it takes for the substance to lose half of its properties or the amount of time it takes for the half of the initial concentrations to be consumed. The equations for half-life are different and they depend on the order of the reaction. As the reaction of crystal violet and sodium hydroxide progressed, the absorbance of the crystal violet decreases with time and is directly related to the concentration of crystal violet. The color of the crystal violet became clearer as the reaction progressed and less and less light was absorbed with time. As the reaction progressed, the and less and less light was absorbed with time....
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This note was uploaded on 04/14/2008 for the course CHEMISTY 10101 taught by Professor Denofrio during the Spring '08 term at University of Illinois at Urbana–Champaign.
- Spring '08