Chem 113 1st Edition Lecture 10 Outline of Last Lecture I. Individual and overall reaction ordersII. Plots of reactant concentration, [A], vs. timeIII. Plots of rate vs. reactant concentration, [A]IV. Effect of concentrations on reaction ratesV. Determining the Rate Law by experimentOutline of Current Lecture VI. Determining Reaction Order and Rate ConstantVII. Kinetics: Rate LawsVIII. Reaction half-lifeCurrent LectureI. Determining Reaction Order and Rate Constanta. Series of plots of concentrations vs. time: Determine the slope of the tangent at TO (initial rate) for each plotb. Initial rates: Compare initial rates when [A] changes and [B] is held constant (and vice versa)c. Rate constant (k) and actual rate law: Substitute initial rates, orders, and concentrations into rate=k [ A ]m[B]n, and solve for kII. Kinetics: Rate Lawsa. For the simple reaction ABi.Rate=−Δ[A]Δt=Δ[B]Δtii.Rate=k [ A]miii. We want a way to predict the concentration of A in timeb. Integrated Rate Lawsi. An integrated rate law includes time as a variable1. First-order rate equation:a.Rate=−∆[A]∆ t=k[A]b.ln[A]o[A]t=ktThese 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.c. Straight line form: ln[A]t= -kt + ln[A]0i. -k is the slop of the lineii. Strong linear correlation supports a first order reactioniii. A plot of ln[A] vs. time gives a straight line for a first-order reaction2. Second-order rate equationa.Rate=−∆[A]∆ t=k [ A ]2b.1[A]t−1[A]0= ktc. Straight line form: 1[ A ]t=kt+1[ A]0d. A plot of 1[ A ]vs. time gives a straight line for a second-order reaction3. Zero-order rate equationa.Rate=−∆[A]∆ t=k [ A ]0b.[ A ]t−[A]0=−ktc. Straight line form: [ A ]t=−kt +[ A ]0d. A plot of [A] vs time gives a straight line for a zero-order reactionIII. Reaction half-lifea. The half-life for a reaction is the time taken for the concentration of a reactant to drop to half its initial valuei. If we observe reaction AB1. t1/2 is the time it take for [ A ]t12[ A ]tinitial=122. Derive half-life using the integrated rate laws for 0, 1st and 2nd order
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