-1 2 3 4 5 7 8 At a certain temperature this reaction follows first-order kinetics with a rate constant of 0.0635 s 2C1,0, (g) →2C1, (g)+50, (g) Suppose a vessel contains C1,0, at a concentration of 1.03 M. Calculate how long it takes for the concentration of C1,0, to decrease by 86.0%. You may assume no other reaction is important. Round your answer to 2 significant digits. e х th E

11.32 The following experimental data were obtained for the reaction 2A + 3 B—C + 2D [A](mol L 1) [B](mol L ’) Rate = A(C]/Af (mol L-1 s-1) 0.127 0.15 0.033 0.127 0.30 0.132 0.255 0.15 0.066 Determine the reaction order for each reactant and the value of the rate constant.

The initial concentration of the reactant in a tirst-order reaction A —» products is 0.64 rnol/L and the half-life is 30.0 s. Calculate the concentration of the reactant exactly 60 s after initiation of the reaction. How long would it take for the concentration of the reactant to drop to one-eighth its initial value? How long would it take for the concentration of the reactant to drop to 0.040 mol/L?

For the reaction A + B C, explain at least two ways in which the rate law could be zero order in chemical A.

One possible mechanism for the decomposition of nitryl chloride, NO2CI, is What is the overall reaction? What rate law would be derived from this mechanism? What effect does increasing the concentration of the product NO2 have on the reaction rate?

The reaction NO(g) + O,(g) — NO,(g) + 0(g) plays a role in the formation of nitrogen dioxide in automobile engines. Suppose that a series of experiments measured the rate of this reaction at 500 K and produced the following data; [NO] (mol L ’) [OJ (mol L 1) Rate = -A[NO]/Af (mol L_1 s-1) 0.002 0.005 8.0 X 10"'7 0.002 0.010 1.6 X 10-'6 0.006 0.005 2.4 X IO-'6 Derive a rate law for the reaction and determine the value of the rate constant.

Kinetics II You and a friend are working together in order to obtain as much kinetic information as possible about the reaction A(g)B(g)+C(g). One thing you know before performing the experiments is that the reaction is zero order, first order, or second order with respect to A. Your friend goes off, runs the experiment, and brings back the following graph. a After studying the curve of the graph, she declares that the reaction is second order, with a corresponding rate law of Rate = k[A]2. Judging solely on the basis of the information presented in this plot, is she correct in her statement that the reaction must be second order? Here are some data collected from her experiment: Time (s) [A] 0.0 1.0 1.0 0.14 3.0 2.5 103 5.0 4.5 105 7.0 8.3 107 b The half-life of the reaction is 0.35 s. Do these data support the reaction being second order, or is it something else? Try to reach a conclusive answer without graphing the data. c What is the rate constant for the reaction? d The mechanism for this reaction is found to be a two-step process, with intermediates X and Y. The first step of the reaction is the rate-determining step. Write a possible mechanism for the reaction. e You perform additional experiments and find that the rate constant doubles in value when you increase the temperature by 10oC. Your lab partner doesnt understand why the rate constant changes in this manner. What could you say to your partner to help her understand? Feel free to use figures and pictures as part of your explanation.

The decomposition of ozone is a second-order reaction with a rate constant of 30.6 atm1 s1 at 95 C. 2O3(g)3O2(g) If ozone is originally present at a partial pressure of 21 torr, calculate the length of time needed for the ozone pressure to decrease to 1.0 torr.

Regular ?ights of supersonic aircraft in the stratosphere ale of concern because such aircraft produce nitric oxide, NO, as a byproduct in the exhaust of their engines. Nitric oxide reacts with ozone, and it has been suggested that this could contribute to depletion of the ozone layer. The reaction NO+O3NO2+O2 is first order with respect to both NO and O3 with a rate constant of 2.20107 L/mol/s. What is the instantaneous rate of disappearance of NO when [NO]=3.3106 M and [O3]=5.9107M?

Isomerization of CH3NC occurs slowly when CH3NC is heated. CH3NC(g) CH3CN(g) To study the rate of this reaction at 488 K, data on [CH3NC] were collected at various times. Analysis led to the following graph. (a) What is the rate law for this reaction? (b) What is the equation for the straight line in this graph? (c) Calculate the rate constant for this reaction. (d) How long does it take for half of the sample to isomerize? (e) What is the concentration of CH3NC after 1.0 104 s?