Chem 113 1st Edition Lecture 9 Outline of Last Lecture I. Expressing the Reaction RateII. The Rate LawOutline of Current Lecture III. Individual and overall reaction ordersIV. Plots of reactant concentration, [A], vs. timeV. Plots of rate vs. reactant concentration, [A]VI. Effect of concentrations on reaction ratesVII. Determining the Rate Law by experimentCurrent LectureI. Individual and overall reaction ordersa. For the reaction 2NO(g)+2H2(g) N2(g)+2H2O(g)i. The rate law: rate=k [ NO]2[ H2]ii. The reaction is in second order with respect to NO, first order with respect to H2 and third order overalliii. Reaction orders must be determined from experimental data, and cannotbe deduced from the balanced equationII. Plots of reactant concentration, [A], vs. timea. Zero-order reaction rates decrease linearlyb. In first-order reaction rates the slope of the tangent lines of the curve gradually decreasesc. In second-order reaction rates, the slope of the tangent lines of the curve decrease more ra[idly than those in first-order reactionsIII. Plots of rate vs. reactant concentration, [A]a. Zero-order reaction rates don’t changeThese 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.rate=k [ A ]0b. First-order reaction rates increase linearlyi.rate=k [ A ]1c. In second-order reaction rates, the slope of the tangent lines of the curve increase graduallyi.rate=k [ A ]2IV. Effect of concentrations on reaction ratesa. For the reaction: NO(g)+O3(g) NO2(g)+O2(g)i.rate=k[NO][O3]ii. The reaction is in 1st order in NO and O3, meaning the rate is proportional to the concentrations [NO] and [O3]iii. The higher the concentration, the more possibilities of collisions between molecules, increasing the rate proportionallyV. Determining the Rate Law by experimenta. For the rate law: rate=k [ NO]m[O2]nb. To find m compare experiments where [NO] changes but [O2] does noti.rate1rate3=([N O]1[NO]3)mii. Plug in all of the supplied values, and solve for miii. Do the same method for finding the value of niv. Plug in the values of m and n, the values for one of the experiments’ concentrations and rate, and solve for kv. Units for the rate constant vary depending on the reaction orders (units inequation are squared or cubed depending on if the reaction order for a concentration is 2nd or 3rd
View Full Document
Unlocking...