Kinetics 1 Consider the following reaction 3A 2B How is the average rate of appearance of B related to the average rate of disappearance of A A B C D E A t B t A t 2 3 B t A t 3 2 B t A t 1 2 B t A t 1 3 B t 2 The combustion of ethylene proceeds by the reaction C2H4 g 3O2 g 2CO2 g 2H2O g When the rate of disappearance of O2 is 0 23 M s 1 what is the rate of appearance of CO2 in M s 1 A B C D E 3 0 15 0 077 0 69 0 35 0 46 Given the following kinetic data for the reaction A B C products Experiment A M B M C M A t M s 1 0 10 0 10 0 10 7 0 10 5 2 0 20 0 10 0 10 1 4 10 4 3 0 10 0 20 0 10 7 0 10 5 4 0 10 0 10 0 20 2 8 10 4 The rate law for this reaction is A Rate k A B C B Rate k A 2 B C Rate k A 2 C D Rate k A B C 2 E None of these is the correct rate law 4 The decomposition of ethanol C2H5OH on an alumina Al2O3 surface was studied at 600K C2H5OH g C2H4 g H2O g Analysis of the data revealed the adjacent straightline plot with a slope of 4 00 x 10 5 M 1s 1 1 C2H5OH If the initial concentration of C2H5OH was 1 25 x 10 2 M calculate the half life for this reaction A B C D E 5 Two substances A and B react with each other in such a way that A is 50 consumed in 33 minutes and 75 consumed in 66 minutes Changing the concentration of B has no effect on the results This reaction is A B C D E 6 2 00 x 106 s 1 73x 104 s 5 73 x 103 s 45 7 s 106 s zero order in both A and B 1st order in both A and B 2nd order in both A and B 1st order in A and zero order in B 2nd order in A and zero order in B It requires 90 0 seconds for a first order reaction to go 25 0 of the way to completion What is the half life of the reaction A B C D E 180 seconds 217 seconds 500 seconds 62 4 seconds None of the above is within 5 of the correct answer Time 7 A second order reaction is observed to be 1 31 times faster at 42 0oC than it is at 30 0oC This means that the activation energy for the reaction is A B C D E 8 236 J mol 23 6 kJ mol 178 J mol 17 9 kJ mol None of the above is within 5 of the correct answer Which of the following statements are correct 1 A reaction is endothermic if the activation energy is greater for the reverse reaction than for the forward reaction 2 A reaction is exothermic if the activation energy is greater for the reverse reaction than for the forward reaction 3 The activated complex is what the reactants are called just before the chemical reaction occurs 4 Formation of the activated complex is what requires the activation energy A B C D E 9 l only 2 only l and 3 only 2 and 3 only 2 and 4 only Below are five statements about the temperature dependence of a reaction rate constant k Which one statement holds true for most chemical reactions A k increases with temperature mainly because there are fewer collisions per second B k increases with temperature mainly because a higher proportion of the collisions are energetic enough to produce reaction C k decreases with T mainly because of the decrease in effectiveness of the attractive long range intermolecular forces D k does not change with temperature E k increases or decreases with temperature depending on whether the reaction is endothermic or exothermic 10 If the reaction aA bB cC is an elementary reaction the most likely values of a and b are A B C D E 11 1 and 1 1 and 2 2 and 1 2 and 2 insufficient information Nitrogen monoxide is reduced by hydrogen to give water and nitrogen by the following reaction 2 H2 g 2 NO g N2 g 2 H2O g For the following proposed mechanism Step 1 fast 2 NO g N2O2 g Step 2 slow N2O2 g H2 g N2O g H2O g Step 3 fast N2O g H2 g N2 g H2O g A B C D E 12 N2O2 is a transition state N2O2 is an activated complex N2O2 is an intermediate N2O2 is a a catalyst N2O2 is both a catalyst and a transition state Two mechanisms have been proposed for the gas phase reaction 2 NO g O2 g 2 NO2 g Scheme I 2 NO g N2O2 g fast N2O2 g O2 g 2 NO2 g slow Scheme II NO g O2 g NO3 g NO3 g NO g 2 NO2 g fast slow Which mechanism is consistent with the observed rate law rate k NO 2 O2 A B C D E Scheme I only Scheme II only Neither Scheme I nor II Both Scheme I and II There is insufficient information to make this determination 13 For the reaction 2 N2O5 g 4 NO2 g O2 g the following mechanism is proposed N2O5 g NO2 g NO3 g NO2 g NO3 g NO2 g NO g O2 g NO3 g NO g 2 NO2 g fast slow fast The observed rate law that is consistent with this mechanism is A B C D E 14 first order in N2O5 first order in NO2 and first order in NO3 first order in NO2 and NO3 and second order in N2O5 second order in N2O5 None of these is consistent with the above mechanism The following reaction is one step in the industrial manufacture of nitric acid 4 NH3 g 5 O2 g 6 H2O g 4 NO g heat The reason for using the Pt catalyst is A to change the standard heat of reaction so as to make the process feasible B to increase the standard entropy change of the reaction which will favor the forward reaction C to absorb the excess heat generated by the reaction D to increase the reaction rate E to eliminate the back reaction 15 Enzymes speed up chemical reactions by a Lowering the energy of the reaction products b Increasing the Arrhenius factor A c Lowering the activation energy Ea A a only B a and b C a and c D b and c E a b and c 16 The decomposition of acetaldehyde CH3CHO can be catalyzed by I2 g uncatalyzed reaction Ea 190 kJ mol CH3CHO g CH4 g CO g catalyzed reaction Ea 136 kJ mol …