CHEM 135 1st Edition Lecture 14 Outline of Last Lecture I Activation in a chemical reaction a Definition b Arrhenius equation c Examples II Reaction mechanism and reaction intermediate a Unimolecular b Bimolecular c Termolecular III Rate determining step and rate law a Example Outline of Current Lecture I Practice Problems II Read section 13 7 and watch video posted on BB Current Lecture 1 Write a balanced reaction for which the following rate relationships are true Rate a b c d 1 N 2 O 5 1 N O2 O 2 2 t 4 t t 2N2O5 4NO2 O2 4NO2 O2 2N2O5 2N2O5 NO2 4O2 NO2 O2 N2O5 2 In the following reaction if H2 reacts at the rate of 0 074 M s i At what rate is ammonia NH3 being formed ii At what rate is N2 reacting These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 3 2 NO H2 N2 2H2O NO H2 Initial Rate M s 0 005 0 002 1 3x10 5 0 01 0 002 5x10 5 0 01 0 004 10x10 5 i ii iii What is the overall order of the reaction What is the rate law of the reaction What is the rate constant iv What is the rate of the reaction when NO 12x10 3M and H2 6x10 3 M 4 The decomposition of SO2Cl2 is first order in SO2Cl2 and has a rate constant of 1 46x10 4s 1 at a certain temperature i What is the half life for this reaction ii How long will it take for the concentration of SO2Cl2 to decrease to 25 of its initial concentration iii If the initial concentration of SO2Cl2 is 1 00M how long will it take for the concentration to decrease to 0 76M iv If the initial concentration of SO2Cl2 is 0 175M what is the concentration after 180s v If the initial concentration is 0 175M what is the concentration after 480s 5 Consider the following three step mechanism for a reaction Cl2 2Cl should be an equilibrium symbol Fast Cl CHCl3 HCl CCl Slow Cl CCl3 CCl4 Fast i What is the overall reaction ii iii Identify the intermediates in the mechanism What is the predicted rate law 6 The kinetics of this reaction was studied as a function of temperature The reaction is first order in each reactant and is second order overall C2H5Br OH C2H5OH Br i ii iii iv Temperature C k L mol x s 25 8 81 x 10 5 35 0 000285 45 0 000854 55 0 00239 65 0 00633 Determine the activation energy for the reaction Determine the frequency factor for the reaction Determine the rate constant at 15 C If a reaction mixture is 0 165M in C2H5Br and 0 240M in OH what is the initial rate of the reaction at 90 C 7 A reaction has a rate constant of 0 0117 M s at 400K and 0 689 M s at 450K i Determine the activation barrier for this reaction ii What is the rate constant at 425K