We typically don't have a value for the frequency factor, A, so we can be creative to determine the activation energy using the two-point method. (This is similar to how we applied the Clausius-Clapeyron equation!) The frequency factor does not depend on temperature, so it will remain constant, as will the activation energy, Ea. Ea (元) In k₂ = In A - Ea B (1) In k₁ = In A Using the equations above, determine an equation for Inby solving both equations above equal for In A and then setting them equal to each other. (check your result with me or one of the

We typically don't have a value for the frequency factor, A, so we can be creative to determine the activation energy using the two-point method. (This is similar to how we applied the Clausius-Clapeyron equation!) The frequency factor does not depend on temperature, so it will remain constant, as will the activation energy, Ea. Ea (元) In k₂ = In A - Ea B (1) In k₁ = In A Using the equations above, determine an equation for Inby solving both equations above equal for In A and then setting them equal to each other. (check your result with me or one of the

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter12: Chemical Kinetics

Section: Chapter Questions

Problem 109CWP: Experiments have shown that the average frequency of chirping by a snowy tree cricket (Oecanthus...

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The rate of photodecomposition of the herbicide piclo- ram in aqueous systems was determined by exposure to sunlight for a number of days. One such experiment produced the following results. (Data from R.T. Hedlun and C.R. Youngson, “The Rates of Photodecomposition of Picloram in Aqueous Systems," Fate of Organic Pesticides in tbe Aquatic Environment, Advances in Chemistry Series, #111, American Chemical Society (1972), 159—172.) Exposure Time, t (days) [Pidoram] (mol L_1) 0 4.14 X 10-6 7 3.70 X 10-6 14 3.31 X 10-6 21 2.94 X 10~6 28 2.61 X 10~6 35 2.30 X 10-6 42 2.05 X 10-6 49 1.82 X 10"6 56 1.65 X 10-6 Determine the order of reaction, the rate constant, and the half-life for the photodecomposition of picloram.
For each of the following reaction diagrams, estimate the activation energy (Ea) of the reaction:
The color change accompanying the reaction of phenolphthalein with strong base is illustrated below. The change in concentration of the dye can be followed by spectrophotometry (Section 4.9), and some data collected by that approach are given below. The initial concentrations were [phenolphthalein] = 0.0050 mol/L and [OH] = 0.61 mol/L. (Data are taken from review materials for kinetics at chemed.chem.purdue.edu.) (For more details on this reaction see L Nicholson, Journal of Chemical Education, Vol. 66, p. 725, 1989.) (a) Plot the data above as [phenolphthalein] versus time, and determine the average rate from t = 0 to t = 15 seconds and from t = 100 seconds to t = 125 seconds. Does the rate change? If so, why? (b) Use a graphical method to determine the order of the reaction with respect to phenolphthalein. Write the rate law, and determine the rate constant. (c) What is the half-life for the reaction?
The oxidation of iodide ion by the hypochlorite ion in the presence of hydroxide ions I(aq) + ClO(aq) IO(aq) + Cl(aq) was studied at 25 C, and the following initial rates data (Y. Chia and R. E. Connick, Journal of Physical Chemistry, Vol. 63, p. 1518, 1959) were collected: (a) Determine the rate law for this reaction. (b) One mechanism that has been proposed for this reaction is the following: Show that the rate law predicted by this mechanism matches the experimentally determined rate law in part a. (Note that when writing the expression for K the equilibrium constant, [H2O] is not involved. See Chapter 15.)
The uncoiling of deoxyribonucleic acid (DNA) is a first-order reaction. Its activation energy is 420 kJ. At 37C, the rate constant is 4.90104min1 (a) What is the half-life of the uncoiling at 37C (normal body temperature)? (b) What is the half-life of the uncoiling if the organism has a temperature of 40C(104F)? (c) By what factor does the rate of uncoiling increase (per C) over this temperature interval?
Experiments have shown that the average frequency of chirping by a snowy tree cricket (Oecanthus fultoni) depends on temperature as shown in the table. Chirping Rate (per min) Temperature (C) 178 25.0 126 20.3 100. 17.3 What is the apparent activation energy of the process that controls the chirping? What is the rate of chirping expected at a temperature of 7.5C?
The activation energy for the decomposition of cyclobutane (C4H8) to ethylene (C2H4) is 261 kJ/mol. If the system produces ethylene at the rate of 0.043 g/s at 500C, what is the rate if the temperature increases to 600C?
When formic acid is heated, it decomposes to hydrogen and carbon dioxide in a first-order decay: HCOOH(g)CO2(g)+H2(g) The rate of reaction is monitored by measuring the total pressure in the reaction container. Time (s) Pressure (torr) 0 220 50 324 100 379 150 408 200 423 250 431 300 435 Calculate the rate constant and half-life in seconds for the reaction. At the start of the reaction (time = 0), only formic acid is present. (HINT: Find the partial pressure of formic acid using Dalton's law of partial pressure and the reaction stoichiometry to find PHCOOH at each time.)
The precipitation of egg albumin in water at 100C has an activation energy of 52.0 kJ/mol. By what percent does the rate of precipitation decrease if the water is at 92C?
Nitroglycerine is an extremely sensitive explosive. In a series of carefully controlled experiments, samples of the explosive were heated to 160 C and their first-order decomposition studied. Determine the average rate constants for each experiment using the following data: Initial [C3H5N3O9] (M) 4.88 3.52 2.29 1.81 5.33 4.05 2.95 1.72 t (s) 300 300 300 300 180 180 180 180 %Decomposed 52.0 52.9 53.2 53.9 34.6 35.9 36.0 35.4
Instantaneous rates for the reaction of hydroxide ion with Cv+ can be determined from the slope of the curve in Figure 11.3 at various concentrations. They are (1) At 4.0 105 mol/L, rate = 12.3 107 mol L1 s1 (2) At 3.0 105 mol/L, rate = 9.25 107 mol L1 s1 (3) At 2.0 105 mol/L, rate = 6.16 107 mol L1 s1 (4) At 1.5 105 mol/L, rate = 4.60 107 mol L1 s1 (5) At 1.0 105 mol/L, rate = 3.09 107 mol L1 s1 (a) What is the relationship between the rates in (1) and (3)? Between (2) and (4)? Between (3) and (5)? (b) What is the relationship between the concentrations in each of these cases? (c) Is the rate of the reaction proportional to the concentration of Cv+? Explain your answer.
The acid-catalyzed iodination of acetone CH3COCH3(aq) + I2(aq) CH3COCH2I(aq) + HI(aq) is a common laboratory experiment used in general chemistry courses to teach the method of initial rates. The reaction is followed spectrophotometrically by the disappearance of the color of iodine in the solution. The following data (J. P. Birk and D. L Walters, Journal of Chemical Education, Vol. 69, p. 585, 1992) were collected at 23 C for this reaction. Determine the rate law for this reaction.