Question 14: In the first order reaction, A->2B, it takes 125 seconds for 20.0 percent of a sample of A to react. What is the value of the rate constant, k? (to 3 significant figures) 0.00227 * /s How long in seconds would it take until 10.0 percent of the original sample of A remained? 1030 × s

Question 14: In the first order reaction, A->2B, it takes 125 seconds for 20.0 percent of a sample of A to react. What is the value of the rate constant, k? (to 3 significant figures) 0.00227 * /s How long in seconds would it take until 10.0 percent of the original sample of A remained? 1030 × s

Chemistry & Chemical Reactivity

10th Edition

ISBN:9781337399074

Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Publisher:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Chapter14: Chemical Kinetics: The Rates Of Chemical Reactions

Section: Chapter Questions

Problem 19PS: Hydrogen peroxide, H2O2(aq), decomposes to H2O() and O2(g) in a reaction that is first-order in H2O2...

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A study of the rate of the reaction represented as 2AB gave the following data: Time (s) 0.0 5.0 10.0 15.0 20.0 25.0 35.0 [A](M) 1.00 0.775 0.625 0.465 0.350 0.205 0.230 (a) Determine the average rate of disappearance of A between 0.0 s and 10.0 s, and between 10.0 s and 20.0 s. (b) Estimate the instantaneous rate of disappearance of A at 15.0 s from a graph of time versus [A]. What are theunits of this rate? (c) Use the rates found in parts (a) and (b) to determine the average rate of formation of B between 0.00 s and 10.0 s, and the instantaneous rate of formation of B at 15.0 s.
The reaction 2 NO(g) + 2 H2(g) N2(g) + 2 H2O(g) was studied at 904 C, and the data in the table were collected. (a) Determine the order of the reaction for each reactant. (b) Write the rate equation for the reaction. (c) Calculate the rate constant for the reaction. (d) Find the rate of appearance of N2 at the instant when [NO] = 0.350 mol/L and [H] = 0.205 mol/L.
In Exercise 11.39, if the initial concentration of N2Oj is 0.100 .\1. how long will it take for the concentration to drop to 0.0100 times its original value? The decomposition of N2O5 in solution in carbon tetrachloride is a first-order reaction: 2N2O5—»4NO2 + O2 The rate constant at a given temperature is found to be 5.25 X 10-4 s-’. If the initial concentration of N2O5 is 0.200 M, what is its concentration after exactly 10 minutes have passed?
Hydrogen iodide decomposes when heated, forming H2(g) and I2(g). The rate law for this reaction is [HI]/t = k[HI]2. At 443C, k = 30. L/mol min. If the initial HI(g) concentration is 1.5 102 mol/L, what concentration of HI(g) will remain after 10. minutes?
Experimental data are listed here for the reaction B: Time (s) IB] (mol/L) 0.00 0.000 10.0 0.326 20.0 0.572 30.0 0.750 40.0 0.890 Prepare a graph from these data, connect the points with a smooth line, and calculate the rate of change of [B] for each 10-s interval from 0.0 to 40.0 s. Does the rate of change decrease from one time interval to the next? Suggest a reason for this result. How is the rate of change of [AJ related to the rate of change of [B] in each time interval? Calculate the rate of change of [AJ for the time interval from 10.0 to 20.0 s. What is the instantaneous rate, A[B]/Ar, when [BI = 0.750 mol/L?
At 573 K, gaseous NO2(g) decomposes, forming NO(g) and O2(g). If a vessel containing NO2(g) has an initial concentration of 1.9 102 mol/L, how long will it take for 75% of the NO2(g) to decompose? The decomposition of NO2(g) is second-order in the reactant and the rate constant for this reaction, at 573 K, is 1.1 L/mol s.
A study of the rate of dimerization of C4H6 gave the data shown in the table: 2C4H6C8H12 (a) Determine the average rate of dimerization between 0 s and 1600 s, and between 1600 s and 3200 s. (b) Estimate the instantaneous rate of dimerization at 3200 s from a graph of time versus [C4H6]. What are the units of this rate? (c) Determine the average rate of formation of C8H12 at 1600 s and the instantaneous rate of formation at 3200 s from the rates found in parts (a) and (b).
Hydrogen iodide, HI, decomposes in the gas phase to produce hydrogen, H2, and iodine, I2. The value of the rate constant, k, fur the reaction was measured at several different temperatures and the data are shown here: Temperature (K) k (M -1 5-1) 555 6.23107 575 2.42106 645 1.44104 700 2.01103 What is the value of the activation energy (in kJ/mol) for this reaction?
For each of the rate laws below, what is the order of the reaction with respect to the hypothetical substances X, Y, and Z? What is the overall order? (a) Rate = k [X][Y][Zl, (b) Rate = k [X]-[Y]1/2[Z], (c) Rate = k [X]L5[Y]-1, (d) Rate = k [X]/[Y]2
Ammonia decomposes when heated according to the equation NH3(g) NH2(g) + H(g) The data in the table for this reaction were collected at a high temperature. Plot In [NH3] versus time and 1/[NH3] versus time. What is the order of this reaction with respect to NH3? Find the rate constant for the reaction from the slope.
Hydrogen peroxide, H2O2(aq), decomposes to H2O() and O2(g) in a reaction that is first-order in H2O2 and has a rate constant k = 1.06 103 min1 at a given temperature. (a) How long will it take for 15% of a sample of H2O2 to decompose? (b) How long will it take for 85% of the sample to decompose?
(a) From data in Table 11.1, calculate the rate of reaction for each time interval: (i) from 40.0 s to 60.0 s; (ii) from 20.0 s to 80.0 s; (iii) from 0.0 to 100.0 s. (b) Use all of the data in the first two columns of Table 11.1 to draw a graph with time on the horizontal (x) axis and concentration on the vertical (y) axis. Draw a smooth curve through the data. On the graph, draw lines that correspond to [Cv+]/t for each interval. (c) Why is the rate not the same for each time interval in part (a), even though the average time for each interval is 50.0 s? (That is, for interval i, the average time is (40.0 s + 60.0 s)/2 = 50.0 s.) Write an explanation of the reason for a friend who is taking this course, and ask your friend to evaluate what you have written.