CHEM 1415 1st EditionLecture 13Unit: Rates of ReactionsOutline of Current Lecture I. Ozone DepletionII. Rates of Chemical Reactionsa. Reaction rateb. Example problemIII. Rate LawsCurrent Lecture Ozone Depletiono Chapman cycle – proposed by British scientist in 1903 1st step is the photochemical dissociation of O2 to form oxygen atoms,which then react and form ozone, O3 Decrease of ozone concentration over Antarctica and North America Rates of Chemical Reactionso Reaction rate - ratio of the change in concentration to the elapsed timerate=change ∈concentrationelapsed time=∆[substance ]∆ tv∏¿ ∆ t∨rate=−∆ [reactant ]∆t=−∆[reactant ]vreact∆ trate=∆ [ product ]∆ t=∆ [ produc t ]¿o Example Problem What is the rate of O2 production if the rate of ozone consumption equals 2.5∗10−5mol L−1s−1 in the reaction of 2O3→3 O2?Rate=−∆ [O3]2 ∆ t=∆[O2]3 ∆ t2.5∗10−5mol L−1s−12=∆ [O2]3 ∆ t∆[O2]∆t=3 (2.5∗10−5mol L−1s−1)2¿3.8∗10−5mol L−1s−1o Average rate – two concentrations are measured at times separated by a finite difference, and the slope of the line between them gives the rateThese 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.o Instantaneous rate – refers to the rate at a single moment, and it is given by the slope of a line tangent to the curve defined b the change in concentration versus time Rate Lawso Rate Law – mathematical equation showing the dependence of reaction rate on concentration Differential rate law – derived from calculus-Rate=k[X]m[Y]n- The actual values of the exponents m and n must be measured
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