Saul Ruiz Chemistry 1BL March 5 2012 Experiment 13 Kinetics This experiment determines the effect of temperature and concentration on the rate of decomposition of hydrogen peroxide as it is catalyzed by potassium iodide Part 1 uses solutions of different concentrations to develop a mechanism to describe the rate of decomposition of H2O2 The general rate law for the decomposition can be written as Rate k H2O2 x I y The solutions of varying concentrations can be expressed by the following chemical equations aq aq H 2 O l IO Step1 H 2 O 2 l I aq aq H 2 O l O2 g I Step 2 H 2 O2 l IO Overall Reaction 2 H 2 O2 l 2 H 2 O l O2 g 2 gas from these reactions was measured to come up with an overall rate The resulting rate mechanism from this experiment was I Rate 5 34 x 10 3 H 2 O2 1 The overall rate for this is 1 195 Increasing the solution concentrations will increase the amount of molecule collisions per unit volume thus increasing the rate of reaction Part Two shows the effect of temperature on the rate of this reaction Increasing temperature will increase the average kinetic energy of the molecules This leads to a higher frequency of collisions for molecules thus increasing the rate of reaction Concentrations are kept the same in order to compare almost identical solutions at varying temperatures The reaction rate for a solution at 22 5 C is 0 0418 mL s Increasing the temperature by 13 5 C increases the rate of reaction by a factor of 1 75 Part Three demonstrates how the catalyst potassium iodide increases the rate of this decomposition A catalyst increases the rate of reaction by providing an alternate path or mechanism that requires less energy for the reaction to occur To measure the initial and final amount of a catalyst titration is used In this case the percent of I recovered was 108 It can be said however that the percent of I recovered is expected to be less than the initial value since in the process of titration a few excess drops are likely to have been used Sources of error in determining the rate of reaction a faulty stopper which may have leaked air from the Erlenmeyer flask When uncapping the stopper gas is inevitably lost Equalizing the water levels in the syringe and burette cannot be very accurate if done manually Also the solution of 4 H2O2 may actually be less than 4 since some of the hydrogen peroxide may have decomposed The water bath and the Erlenmeyer flask might also not have been the same temperature The R squared value for the rate data ranged from 0 9834 to 0 9992 The closer this value is to 1 the more accurate this data will result Seeing that these R squared values are very close to 1 it can be said there is little to no deviation of the results from a straight line Some sources of error in determining the percent iodide recovered may include that it is highly likely that excess drops will be augmented in the titration therefore giving a value less than the original amount