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Problem 1
Use the following equation and graph to answer questions 1 and 2. Hydrogen iodide decomposes at 410 °C, according the reaction: 2 HI1g2¡H21g2 + I21g2 The graph shows how the concentration of HI changes over time. What is the average rate of loss of HI over the time period 0–40 s (LO 14.1) (a) 7.5 * 10-3 M>s (b) 4.8 * 10-3 M>s (c) 3.0 * 10-2 M>s (d) 3.5 * 10-3 M>sProblem 8
The gas phase decomposition of HI has the following rate law: 2 HI1g2¡H21g2 + I21g2 Rate = k3HI42 At 443 °C, k = 30.1 M-1 min-1. If the initial concentration of HI is 0.010 M, what is the concentration after 1.5 hours? (LO 14.8) (a) 6.9 * 10-3 M (b) 1.8 * 10-3 M (c) 3.6 * 10-4 M (d) 8.9 * 10-4 MProblem 9
Chlorine monoxide (ClO) decomposes at room temperature according to the reaction 2 ClO1g2¡Cl21g2 + O21g2 The concentration of ClO was monitored over time, and three graphs were made:
What is the rate law for the reaction? (LO 14.9) (a) Rate = k (b) Rate = k3ClO4 (c) Rate = k3ClO42 (d) Rate = k3ClO43 M14_MCMU6230_
Problem 11
A key reaction in the upper atmosphere is O31g2 + O1g2 ¡ 2 O21g2 For this process, the energy of activation for the forward reaction, Ea1fwd2, is 19 kJ/mol, and the enthalpy change for the reaction, ΔHrxn, is -392 kJ>mol. What is the energy of activation for the reverse reaction, Ea1reverse2? (LO 14.10) (a) 411 kJ/mol (b) 392 kJ/mol (c) 373 kJ/mol (d) 196 kJ/molProblem 13
To answer questions 13–15, refer to the mechanism: H2O21aq2 + I-1aq2¡OH-1aq2 + HOI1aq2 Slower, rate-determining HOI1aq2 + I-1aq2¡OH-1aq2 + I21aq2 Faster 2 OH-1aq2 + 2 H3O+1aq2¡4 H2O1l2 Faster Identify the catalyst and intermediate(s) in the mechanism. (LO 14.12, 14.16) (a) Catalyst = I-, intermediates = OH-, HOI (b) Catalyst = H3O+, intermediate = HOI (c) No catalyst, intermediate = I2 (d) No catalyst, intermediates = OH-, HOIProblem 14.56a
Ammonia is manufactured in large amounts by the reaction
N2(g) + 3 H2(g) → 2 NH3(g)
(a) How is the rate of consumption of H2 related to the rate of consumption of N2?
Problem 39
(b) Write the balanced reaction that corresponds to the data in the graph.
Problem 40a
The following reaction is first order in A (red spheres) and first order in B (blue spheres): A + B → Products Rate = k[A][B]
(a) What are the relative rates of this reaction in vessels (1)–(4)? Each vessel has the same volume.
Problem 40b
The following reaction is first order in A (red spheres) and first order in B (blue spheres): A + B → Products Rate = k[A][B]
(b) What are the relative values of the rate constant k for vessels (1)–(4)?
Problem 41
Consider the first-order decomposition of A molecules (red spheres) in three vessels of equal volume. (1)-(3)
(c) How will the rates and half-lives be affected if the volume of each vessel is decreased by a factor of 2?
Problem 41b
Consider the first-order decomposition of A molecules (red spheres) in three vessels of equal volume. (1)-(3)
(b) What are the relative half-lives of the reactions in vessels (1)–(3)?
Problem 42
Consider the first-order reaction AS B in which A molecules (red spheres) are converted to B molecules (blue spheres).
(a) Given the pictures at t = 0 min and t = 1 min, draw pictures that show the number of A and B molecules present at t = 2 min and t = 3 min.
Problem 43b
The following pictures represent the progress of the reaction AS B in which A molecules (red spheres) are converted to B molecules (blue spheres).
(b) Draw a picture that shows the number of A and B molecules present at t = 3 min.
Problem 43c
The following pictures represent the progress of the reaction AS B in which A molecules (red spheres) are converted to B molecules (blue spheres).
(c) Suppose that each sphere represents 6.0⨉1021 molecules and that the volume of the container is 1.0 L. What is the rate constant for the reaction in the usual units?
Problem 44
The following pictures represent the progress of a reaction in which two A molecules combine to give a more complex molecule A2, 2 AS A2.
(b) What is the rate law?
Problem 45
What is the molecularity of each of the following elementary reactions? (a)
(b)
(c)Problem 46
The relative rates of the reaction A + B S AB in vessels (1)–(3) are 4:4:1. Red spheres represent A molecules, and blue spheres represent B molecules. (1)-(3)
(a) What is the order of the reaction in A and B?
Problem 48b
Consider a reaction that occurs by the following mechanism:
A + BC → AC + B
AC + D → A + CD
The potential energy profile for this reaction is as follows:
(b) Write structural formulas for all species present at reaction stages 1–5. Identify each species as a reactant, product, catalyst, intermediate, or transition state.
Problem 48c
Consider a reaction that occurs by the following mechanism:
A + BC → AC + B
AC + D → A + CD
The potential energy profile for this reaction is as follows:
(c) Which of the two steps in the mechanism is the rate-determining step? Write the rate law for the overall reaction.
Problem 48d
Consider a reaction that occurs by the following mechanism:
A + BC → AC + B
AC + D → A + CD
The potential energy profile for this reaction is as follows:
(d) Is the reaction endothermic or exothermic? Add labels to the diagram that show the values of the energy of reaction ΔE and the activation energy Ea for the overall reaction.
Problem 49
Draw a plausible transition state for the bimolecular reaction of nitric oxide with ozone. Use dashed lines to indicate the atoms that are weakly linked together in the transition state. NO(g) + O3(g) NO2(g) + O2(g)
Problem 52
Use the information in Table 14.1 and Figure 14.1 to estimate the instantaneous rate of appearance of NO2 at t = 350 s by calculating the average rate of appearance of NO2 over the following time intervals centered on t = 350 s. (a) 0 to 700 s (b) 100 to 600 s (c) 200 to 500 s (d) 300 to 400 s Which is the best estimate, and why?Problem 54a
From the plot of concentration–time data in Figure 14.1, estimate: (a) the instantaneous rate of decomposition of N2O5 at t = 200 s.
Problem 54b
From the plot of concentration–time data in Figure 14.1, estimate: (b) the initial rate of decomposition of N2O5.
Problem 55a
From a plot of the concentration–time data in Worked Example 14.9, estimate: (a) the instantaneous rate of decomposition of NO2 at t = 100 s.
Problem 55b
From a plot of the concentration–time data in Worked Example 14.9, estimate: (b) the initial rate of decomposition of NO2.
Problem 56
Ammonia is manufactured in large amounts by the reaction N21g2 + 3 H21g2S 2 NH31g2 (b) How is the rate of formation of NH3 related to the rate of consumption of N2?Problem 58
Chlorite is reduced by bromide in acidic solution according to the following balanced equation: ClO2 -1aq2 + 4 Br-1aq2 + 4 H+1aq2S Cl-1aq2 + 2 Br21aq2 + 2 H2O1l2 (a) If Δ3Br24>Δt = 4.8 * 10-6 M>s, what is the value of Δ3ClO2 -4>Δt during the same time interval?Problem 61
The reaction 2NO1g2 + 2 H21g2S N21g2 + 2 H2O1g2 is first order in H2 and second order in NO. Write the rate law, and specify the units of the rate constant.Problem 66
Initial rate data at 25 °C are listed in the table for the reaction NH4 +1aq2 + NO2 -1aq2S N21g2 + 2 H2O1l2(b) What is the value of the rate constant?
