Chem 113 1st Edition Lecture 14 Outline of Last Lecture I. The rate-determining step of a reactionII. Pseudo-First-Order ReactionsIII. Reaction energy diagram for two-step reactionOutline of Current Lecture I. Probability of a mechanismII. Determining rate law from multi-step reactionsIII. Decomposition of O3 to O2IV. Catalysis: speeding up a reactionCurrent LectureI. Probability of a mechanisma. Termolecular reactions are highly unlikely to occurb. Bimolecular reactions are much more likely to occurII. Determining rate law from multi-step reactionsa. Find the elementary rate law for each step, and determine whether or not cancellations must be madei. Rate laws are based off reactants, replace the product with a reactant if necessarrt1. Example:a. 2NON2O2 (rate=[NO]2)N2O2+O22NO2 (rate=[N2O2][O2])2NO+O2 NO2 (rate=[NO]2[O2])III. Decomposition of O3 to O2a. The following sequence of reaction describes the decomposition of O3These 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.i. O3+ClClO+O2ClO+O3Cl+2O22O33O2 (Balanced overall equation)ii. Chlorine acts as a catalyst during this reaction1. Used as a reactant in the first reaction, is released as a product (catalysts are never consumed)2. Speeds up the reaction by lowering activation energyIV. Catalysis: speeding up a reactiona. A catalyst increases the reaction rate without itself being consumed in the reactionb. Catalysts provide a different reaction pathway with lower total activation energythan the uncatalyzed reactionc. Speeds upi. Forward reactionii. Reverse reactiond. Does not effecti. ΔH, ΔGii. Equilibrium position (K)e. Can change reaction progress profilef. Homogeneous catalysis: when catalyst is in the same phase as the reactantg. Heterogeneous catalysis: when the catalyst is in a different phase from the reactantsi. Usually a solid catalyst and gas or solution reactantii. Reaction happens on the surface of the
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