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Ch.14 - Chemical Kinetics
All textbooksBrown 14th EditionCh.14 - Chemical KineticsProblem 82
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Chapter 14, Problem 82

(b) Automobile catalytic converters have to work at high temperatures, as hot exhaust gases stream through them. In what ways could this be an advantage? In what ways a disadvantage? (c) Why is the rate of flow of exhaust gases over a catalytic converter important?

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Step 1: Understand the function of a catalytic converter. Catalytic converters are devices used in automobiles to reduce harmful emissions by converting pollutants in exhaust gases into less harmful substances through chemical reactions.
Step 2: Consider the advantages of high temperatures in catalytic converters. High temperatures can increase the rate of chemical reactions, making the catalytic converter more efficient at converting pollutants into less harmful substances.
Step 3: Consider the disadvantages of high temperatures in catalytic converters. High temperatures can lead to thermal degradation of the catalyst materials, reducing the lifespan of the catalytic converter and potentially leading to the release of pollutants if the converter fails.
Step 4: Analyze the importance of the rate of flow of exhaust gases. The rate of flow affects the contact time between the exhaust gases and the catalyst. Optimal flow rates ensure sufficient contact time for effective conversion of pollutants.
Step 5: Discuss the balance needed in the flow rate. If the flow rate is too high, there may not be enough time for the reactions to occur, reducing efficiency. If too low, it could lead to back pressure and reduced engine performance.
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Related Practice
Open Question
The oxidation of SO2 to SO3 is accelerated by NO2. The reaction proceeds according to: NO2(g) + SO2(g) → NO(g) + SO3(g) 2 NO(g) + O2(g) → 2 NO2(g) (a) Show that, with appropriate coefficients, the two reactions can be summed to give the overall oxidation of SO2 by O2 to give SO3. (d) Is this an example of homogeneous catalysis or heterogeneous catalysis?
Textbook Question

The addition of NO accelerates the decomposition of N2O, possibly by the following mechanism: NO1g2 + N2O1g2¡N21g2 + NO21g2 2 NO21g2¡2 NO1g2 + O21g2 (b) Is NO serving as a catalyst or an intermediate in this reaction?

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Textbook Question

Many metallic catalysts, particularly the precious-metal ones, are often deposited as very thin films on a substance of high surface area per unit mass, such as alumina 1Al2O32 or silica 1SiO22. (b) How does the surface area affect the rate of reaction?

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Open Question
The enzyme carbonic anhydrase catalyzes the reaction CO2(g) + H2O(l) ↔ HCO3⁻(aq) + H⁺(aq). In water, without the enzyme, the reaction proceeds with a rate constant of 0.039 s⁻¹ at 25 _x001E_C. In the presence of the enzyme in water, the reaction proceeds with a rate constant of 1.0 * 10⁶ s⁻¹ at 25 _x001E_C. Assuming the collision factor is the same for both situations, calculate the difference in activation energies for the uncatalyzed versus enzyme-catalyzed reaction.
Textbook Question

The enzyme urease catalyzes the reaction of urea, 1NH2CONH22, with water to produce carbon dioxide and ammonia. In water, without the enzyme, the reaction proceeds with a first-order rate constant of 4.15 * 10-5 s-1 at 100 C. In the presence of the enzyme in water, the reaction proceeds with a rate constant of 3.4 * 104 s-1 at 21 C. (c) In actuality, what would you expect for the rate of the catalyzed reaction at 100 C as compared to that at 21 C?

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Textbook Question

The activation energy of an uncatalyzed reaction is 95 kJ/mol. The addition of a catalyst lowers the activation energy to 55 kJ/mol. Assuming that the collision factor remains the same, by what factor will the catalyst increase the rate of the reaction at (a) 25 C

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