Week 2- Reaction Rate
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This 2 page Class Notes was uploaded by BettyAnn Mead on Friday January 30, 2015. The Class Notes belongs to 112 at University of Massachusetts taught by Voigtman in Spring2015. Since its upload, it has received 111 views.
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Date Created: 01/30/15
Method for Initial Rate 0 Used to determine exponents and k 0 How it is done 0 Assume aA bB l cC fF 0 Pick a convenient variable For Example Choose A Rate 1adAdt Prepare solutions At t0 mix solution Remember dilutions 0 After a short time measure A again RatekAquotxBquotyCquotz o x y 2 FIRST 0 k SECOND Integrated Rate Law 0 Used to determine reaction orders and the rate constant Tes us the rate of change of concentration of reactants and products vs time If x1 special case then nAtkt Alo m1 is the rst order of kinetics If m0 Then AtAokt If m2 Then 1At1Aokt COO Half Life T12 is the time required for a reactants concentration or amount to decrease to half of it initial value 0 1st Order Reaction l lnAtAokt Radioactive Elements have SHORT Half Lives How can half lives tell you the order of a reaction 0 Determine how long it takes for the original amount to decrease by 50 Initial Half Life 0 Determine the second half life when the previous amount decreases by 50 o If the second half life is equal to the initial half life then the reaction is rst order 0 If the second half life is half of the initial half life then the reaction is zero order 0 If the second half life is half of the initial half life the reaction is second order Collision Theory of Reaction Rates Reacting molecules must collide Colliding molecules must have enough energy to initiate bond breaking and bond formation Colliding molecules must have correct orientations that can lead to rearrangement to form products Temperature Reaction Rate and Activation Energy 0 Raising temperature increases the proportion of reactant molecules that can react