CHEM 102 1nd Edition Lecture 14 Outline of Last Lecture I. Reactions RatesII. Rate LawsOutline of Current Lecture I. Rate Constant KII. Kinetics So FarIII. Concentration vs Time: Integrated Rate LawsIV. Zero-Order ReactionsV. First-Order ReactionsVI. Second-Order ReactionsVII. Use What You Now KnowCurrent LectureI. Rate Constant K- The constant K: Is specific to each experiment Formed from experimental data Does not change with initial concentration Does not change with time Changes with temperature Changes because of catalysts Units will depend on the overall order of the reaction The unit will usually be one power less than the overall order Example: Which unit would be for rate constant in rate expression for the third order? Answer: L2 mol-2 s-1 Worked out to the side Always have positive ratesII. Kinetics So Far- You can get the rate of reaction from: Equations – the rate in terms ofproduct and reactantsThese 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. Graphs – time and concentration data with tangent lines and the slope between two times Experiments III. Concentration vs Time: Integrated Rate Laws- Allows for the determination of reactants or products at a specific time- Allows for the determination of half life (t1/2)- Integrated rate equation and half life depend on the overall reaction orderIV. Zero-Order Reactions- Rate law for zero order where (aA B)- Rate = k[A]0; therefore Rate = k- Integrated rate law: [A] = -akt + [A]o (to graph use y = mx + b where m is –ak)V. First-Order Reactions- Rate law for first order reaction (aA B) is k[A]- Integrated rate law: ln [A] = -akt + ln[A]oVI. Second-Order Reactions- Rate law = k[A]2- Integrated rate law: 1[ A ]= akt +1[ A ]OVII. Use What You Now Know- Use the first order integrated rate equation Ln(N2O5) = -akt + ln(N2O5) Find how many moles are left at 60 seconds with 2.50 moles of N2O5 in 5L where the rate constant is 0.00840 s-1. Determine the molarity Then “plug and chug”Order “y”Zero [A]First ln[A]Third1[ A
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