Iodine Clock Reaction：碘钟反应

Iodine Clock Reaction：碘钟反应 Name:_______________________________ The Iodination of Acetone: a Kinetics Study In this experiment, you will be characterizing the kinetics of a well-known reaction involving the iodination of acetone (CHCOCH): 33 --+CHCOCH + I + HCl , CHCOCHI + I + Cl + 2H 33232 Your assignment is to experimentally determine the simple rate law for this reaction, including calculation of all of the appropriate orders and the rate constant. It will be easy to follow the progress of this reaction as iodine is brownish in solution, but all of the products of this reaction are colorless. To estimate the rate of reaction in each trial, you will see how long it takes for the iodine in the solution to be consumed. Since the transition from brown , colorless isn’t immediate, both lab partners should be involved in the timing process. Because the concentration of I is significantly less than that of the acetone and hydrochloric acid, 2 this rate, (-,[I]/ ,t), can be used to approximate the initial rate of reaction in each trial. 2 Subsequently you will use this initial rate to construct an initial rate table. Use that table to then determine rate orders for each reactant. Objective: , Determine the simple rate law for the iodination of acetone , Calculate the rate constant k. Chemicals and materials available: 0.00500 M I test tubes 2 4.00 M acetone beakers and flasks 3.00 M HCl 5.0 mL serological pipettes stopwatches Some things to think about… , The ONLY rate-affecting factors that should be manipulated by you are concentrations of reactant. Don’t stir or shake the contents of the beaker, and don’t change the temperature. , Water should be used as necessary to alter the concentrations of reactant from trial to trial without changing the total volume of solution (which should always be 10.0 mL) , Run two trials for each experiment (there will be 8 trials in all) , Think about how to get all three reactants into the same vessel simultaneously , Use the two blank charts below to record your data. o What is the starting (initial) concentration of each reactant? o What is the rate of reaction for each trial? , Calculate the rate constant k for the reaction. , 50 mL of each stock solution should last the entire lab. I. Determining concentrations of reactant after dilution (using 4.00 M acetone, 0.0050 M I, 2 and 3.00 M HCl) *see sample calculation for HCl in trial 1 below… Volume [acetone] Volume [HCl] Volume [I] Volume Total Vol. 2Trial Acetone HCl Iodine HO 2 (baseline) 10.0 mL 0.00125 M 1 2.50 mL 2.50 mL 2.50 mL 2.50 mL 1.00 M 0.750 M* (baseline) 10.0 mL 0.00125 M 2 2.50 mL 2.50 mL 2.50 mL 2.50 mL 1.00 M 0.750 M* 10.0 mL 3 5.00 mL 2.50 mL 2.50 mL - 0 - 10.0 mL 4 5.00 mL 2.50 mL 2.50 mL - 0 - 10.0 mL 5 10.0 mL 6 10.0 mL 7 10.0 mL 8 3.00 mol HCl0.00750 mol HCl,,* .00250 L HCl 0.00750 mol HCl , so... 0.750 M HCl，,,,,1 L solution0.0100 L solution,, OR 2.50 mL HCl,, ，, 3.00 M 0.750 M HCl,,10.0 mL solution,, II. Determination of Orders mnp Rate = k[acetone][I][HCl] 2 Rate = Average Rate = Trial [acetone] [HCl] [I] , [I]/ ,t , [I]/ average ,t 222 1 2 3 4 5 6 7 8