Iodine Clock Reaction

Iodine Clock Reaction - Experiment 14: Kinetics: The...

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Experiment 14: Kinetics: The Iodine Clock Reaction Theory In Chemistry, the study of kinetics involves investigating the rates at which reactions occur and how those rates are affected by changes in the temperature, pressure, concentration, and presence of a catalyst. These rates can be determined by measuring the time interval of the reaction under various conditions of concentration and temperature. The rate of a reaction also depends on the rate constant and the orders of reactions. In addition to those, there also must be a minimum amount of energy between the reactants to create products; this amount of energy is called the activation energy of the reaction. With use of a catalyst, this activation energy can be lowered, which as a result increases the rate of the reaction. In this experiment, the order of reaction will be determined with respect to iodide in Part A and with respect to peroxydisulfate Part B. In part C, the activation energy of the reaction will be determined by calculating the slope of a plot of ln k versus 1/t. And finally in Part D, the effect of a catalyst in the reaction will be observed. Formulas used in Calculations and Reactions run Rate law: k [ -] [ - ] I a S2O8 2 b a = order with respect to iodide b= order with respect to peroxydisulfate Arrhenius equation: k = A - / e Ea RT k= rate constant R= Gas law constant Ea= activation energy T= temperature in Kelvin Rearranged to show how k varies with T: ln k = - ( ) EaRT 1T + ln A [ - ] Δ S2O8 2 = - - - - VS2O3 2 MS2O3 21 mol S2O8 22 mol S2O3 2V total Reactions run:
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Procedure Part A 1. Follow table 1 for amount of reagents used for each run 2. Add first four reagents (Starch, Na2S2O3, KI, KNO3) into a 100mm test tube 3. Add last two reagents ((NH4)2S2O8, (NH4)2SO4)) into a second 100mm test tube 4. Pour the contents of the second tube of reagents into the first and start the timer 5. Pour back and forth three times and observe the solution until a dark blue color appears 6. Stop the timer and note the elapsed time from the first mixing. 7. Repeat each run again in duplicate Table 1. Reagent volumes for determining the Order with Respect to Iodide mL Ru n .2% Starch .012M Na2S2O3 .20M KI .20M KNO3 .20M (NH4)2S2O8 .20M (NH4)2SO4) 1 0.10 0.20 0.80 0.00 0.40 0.40 2 0.10 0.20 0.40 0.40 0.40 0.40 3 0.10 0.20 0.20 0.60 0.40 0.40 4 0.10 0.20 0.10 0.70 0.40 0.40 Part B 1. Follow table 2 for amounts of reagents used in each run
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2. Follow same pipetting procedure from part A for runs 5-8 Table 2. Reagent volumes for determining the Order with Respect to Peroxydisulfate mL
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This note was uploaded on 02/28/2011 for the course CHEM 1A taught by Professor Fisher during the Winter '10 term at DeAnza College.

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Iodine Clock Reaction - Experiment 14: Kinetics: The...

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