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문제 55b
The gas-phase reaction Cl(g) + HBr(g) → HCl(g) + Br(g) has an overall energy change of -66 kJ. The activation energy for the reaction is 7 kJ. (b) What is the activation energy for the reverse reaction?
- For the elementary process N2O5(g) → 2NO2(g) + NO3(g), the activation energy (Ea) and overall ΔE are 154 kJ/mol and 136 kJ/mol, respectively. (a) Sketch the energy profile for this reaction, and label Ea and ΔE.
문제 56
- Indicate whether each statement is true or false. (a) If you compare two reactions with similar collision factors, the one with the larger activation energy will be slower. (b) A reaction that has a small rate constant must have a small frequency factor.
문제 57
문제 57c
Indicate whether each statement is true or false. (c) Increasing the reaction temperature increases the fraction of successful collisions between reactants.
문제 58a
Indicate whether each statement is true or false. (a) If you measure the rate constant for a reaction at different temperatures, you can calculate the overall enthalpy change for the reaction.
문제 58b
Indicate whether each statement is true or false. (b) Exothermic reactions are faster than endothermic reactions.
문제 58c
Indicate whether each statement is true or false. (c) If you double the temperature for a reaction, you cut the activation energy in half.
문제 59
Based on their activation energies and energy changes and assuming that all collision factors are the same, rank the following reactions from slowest to fastest. (a) Ea = 45 kJ>mol; E = -25 kJ>mol (b) Ea = 35 kJ>mol; E = -10 kJ>mol (c) Ea = 55 kJ>mol; E = 10 kJ>mol
- (a) A certain first-order reaction has a rate constant of 2.75 * 10^-2 s^-1 at 20 _x001E_C. What is the value of k at 60 _x001E_C if Ea = 75.5 kJ/mol? (b) Another first-order reaction also has a rate constant of 2.75 * 10^-2 s^-1 at 20 _x001E_C. What is the value of k at 60 _x001E_C if Ea = 125 kJ/mol?
문제 61
- Understanding the high-temperature behavior of nitrogen oxides is essential for controlling pollution generated in automobile engines. The decomposition of nitric oxide (NO) to N2 and O2 is second order with a rate constant of 0.0796 M-1s-1 at 737 _x001E_C and 0.0815 M-1s-1 at 947 _x001E_C. Calculate the activation energy for the reaction.
문제 62
- The rate of the reaction CH3COOC2H5(aq) + OH-(aq) → CH3COO-(aq) + C2H5OH(aq) was measured at several temperatures, and the following data were collected: Temperature (°C) k (M⁻¹ s⁻¹) 15 0.0521 25 0.101 35 0.184 45 0.332. Calculate the value of Ea by constructing an appropriate graph.
문제 63
문제 64
The temperature dependence of the rate constant for a reaction is tabulated as follows: Temperature (K) k 1M 1 s1 2 600 0.028 650 0.22 700 1.3 750 6.0 800 23 Calculate Ea and A.
- What is meant by the term elementary reaction? What is a reaction mechanism? What is meant by the term rate-determining step?
문제 65
문제 65b
(b) What is the difference between a unimolecular and a bimolecular elementary reaction?
- (a) Can an intermediate appear as a reactant in the first step of a reaction mechanism? (b) On a reaction energy profile diagram, is an intermediate represented as a peak or a valley?
문제 66
문제 67a
What is the molecularity of each of the following elementary reactions? Write the rate law for each. (a) Cl2(g) → 2 Cl(g)
문제 67b
What is the molecularity of each of the following elementary reactions? Write the rate law for each. (b) OCl-(aq + H2O(l) → HOCl(aq) + OH-(aq)
문제 67c
What is the molecularity of each of the following elementary reactions? Write the rate law for each. (c) NO(g) + Cl2(g) → NOCl2(g)
문제 68a,b
What is the molecularity of each of the following elementary reactions? Write the rate law for each.
(a) 2 NO(g) → N2O2(g)
(c) SO3(g) → SO2(g) + O(g)
문제 68b
What is the molecularity of each of the following elementary reactions? Write the rate law for each. (b)
문제 69a
(a) Based on the following reaction profile, how many intermediates are formed in the reaction A→D?
문제 69c
(c) Which step is the fastest?
문제 70a
Consider the following energy profile.
(a) How many elementary reactions are in the reaction mechanism?
문제 70b
Consider the following energy profile.
(b) How many intermediates are formed in the reaction?
문제 70c
Consider the following energy profile.
(c) Which step is rate limiting?
- The following mechanism has been proposed for the gas-phase reaction of H2 with ICl: H2(g) + ICl(g) → HI(g) + HCl(g), HI(g) + ICl(g) → I2(g) + HCl(g). (c) If the first step is slow and the second one is fast, which rate law do you expect to be observed for the overall reaction?
문제 71
문제 72a
The decomposition of hydrogen peroxide is catalyzed by iodide ion. The catalyzed reaction is thought to proceed by a two-step mechanism:
H2O2(aq) + I-(aq) → H2O(l) + IO-(aq) (slow)
IO-(aq) + H2O2(aq) → H2O(l) + O2(g) + I-(aq) (fast)
(a) Write the chemical equation for the overall process.
문제 72b
The decomposition of hydrogen peroxide is catalyzed by iodide ion. The catalyzed reaction is thought to proceed by a two-step mechanism:
H2O2(aq) + I-(aq) → H2O(l) + IO-(aq) (slow)
IO-(aq) + H2O2(aq) → H2O(l) + O2(g) + I-(aq) (fast)
(b) Identify the intermediate, if any, in the mechanism.
문제 72c
The decomposition of hydrogen peroxide is catalyzed by iodide ion. The catalyzed reaction is thought to proceed by a two-step mechanism:
H2O2(aq) + I-(aq) → H2O(l) + IO-(aq) (slow)
IO-(aq) + H2O2(aq) → H2O(l) + O2(g) + I-(aq) (fast)
(c) Assuming that the first step of the mechanism is rate determining, predict the rate law for the overall process.
문제 73a
The reaction 2 NO1g2 + Cl21g2¡2 NOCl1g2 was performed and the following data were obtained under conditions of constant 3Cl24:
![Graph showing the linear relationship of ln[H2] over time in chemical kinetics.](https://lightcat-files.s3.amazonaws.com/problem_images/b13cc8f7b3c6acff-1666285465032.jpg)
(a) Is the following mechanism consistent with the data? NO1g2 + Cl21g2ΔNOCl21g2 1fast2 NOCl21g2 + NO1g2¡2 NOCl1g2 1slow2