Lecture 6 - 1/18/10 The decomposition of 2 HI (g) ! H2 (g)...

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1/18/10 1 The decomposition of 2 HI (g) ! H 2 (g) + I 2 (g) has a rate constant of 9.51 x 10 -9 M -1 s -1 at 500 K and 1.10 x 10 -5 M -1 s -1 at 600 K. At what temperature is the rate constant 2.0 x 10 -4 M -1 s -1 ? A) 557 K B) 200 K C) 473 K D) 654 K E) 398 K 60 2.0 x 10 -4 M -1 s -1 > 1.10 x 10 -5 M -1 s -1 Therefore, T > 600 K Rate increases with temperature 61 ln k 2 k 1 ! " # \$ % & = E a R 1 T 1 1 T 2 ! " # \$ % & 1 T 2 = 1 T 1 ! R E a ln k 2 k 1 " # \$ % & If we were only given the information on the previous slide, would first have to solve for E a (multi-step problem common on exams) Equation from data sheet: Rearrange to solve for 1/T 2 : = 0.00152 K ! 1 = 1 600 ! 8.31447 J /( molK ) 176000 J / mol ln 2.0 " 10 ! 4 1.10 " 10 ! 5 # \$ % & ( T 2 = 654 K Use data from T = 600 K (could use data from 500 K) 4. Effect of Temperature/Concentration on Rates (Section 16-6) Why do reaction rates increase when T is increased ? k = Ae ! E a / RT Arrhenius Equation 4.A. Collision Theory - molecules must collide to react - Higher concentration = more collisions - Higher T = more collisions - Higher T = increased kinetic energy Do all collisions lead to reactions?

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This note was uploaded on 04/22/2010 for the course CHEM 102 taught by Professor Brown during the Winter '10 term at University of Alabama at Birmingham.

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Lecture 6 - 1/18/10 The decomposition of 2 HI (g) ! H2 (g)...

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