(a)
Interpretation:
A rough sketch of the energy profile for a reaction in which
Concept Introduction:
An energy profile is used to represent a single energetic pathway, containing the reaction coordinate, in which reactants are converted into products.
(b)
Interpretation:
A rough sketch of the energy profile for a reaction in which
Concept Introduction:
An energy profile is used to represent a single energetic pathway, containing the reaction coordinate, in which reactants are converted into products.
(c)
Interpretation:
A rough sketch of the energy profile for a reaction in which
Concept Introduction:
An energy profile is used to represent a single energetic pathway, containing the reaction coordinate, in which reactants are converted into products.
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Chemical Principles
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- The decomposition of NH3 to N2 and H2 was studied on two surfaces: Surface Ea (kJ/mol) W 163 Os 197 Without a catalyst, the activation energy is 335 kJ/mol. a. Which surface is the better heterogeneous catalyst for the decomposition of NH3? Why? b. How many times faster is the reaction at 298 K on the W surface compared with the reaction with no catalyst present? Assume that the frequency factor A is the same for each reaction. c. The decomposition reaction on the two surfaces obeys a rate law of the form Rate=k[NH3][H2] How can you explain the inverse dependence of the rate on the H2 concentration?arrow_forwardAt 620. K butadiene dimerizes at a moderate rate. The following data were obtained in an experiment involving this reaction: t(s) [C4H6] (mol/L) 0 0.01000 1000.. 0.00629 2000. 0.00459 3000. 0.00361 a. Determine the order of the reaction in butadiene. b. In how many seconds is the dimerization 1.0% complete? c. In how many seconds is the dimerization 10.0% complete? d. What is the half-life for the reaction if the initial concentration of butadiene is 0.0200 M? e. Use the results from this problem and Exercise 45 to calculate the activation energy for the dimerization of butadiene.arrow_forward11.44 A possible reaction for the degradation of the pesticide DDT to a less harmful compound was simulated in the laboratory. The reaction was found to be first order, with k = 4.0 X 10_H s"' at 25°C. What is the half-life for the degradation of DDT in this experiment, in years?arrow_forward
- Consider a hypothetical reaction between A and B: A + B products Use the following initial rate data to calculate the rate constant for this reaction. [A] (mol/L) [B] (mol/L) Initial Rate (mol/L s) 0.20 1.0 3.0 0.50 1.0 11.8 2.0 2.0 189.5arrow_forwardNitrogen monoxide is reduced by hydrogen to give nitrogen and water: 2 NO(g) + 2 H2(g) N2(g) + 2 H2O(g) One possible mechanism for this reaction involves the following reactions: 2 NO(g) N2O2(g) N2O2(g) + H2(g) N2O(g) + H2O(g) N2O(g) + H2(g) N2(g) + H2O(g) What is the molecularity of each of the three steps? What is the rate equation for the third step? Identify the intermediates in this reaction; how many different intermediates are there? Show that the sum of these elementary steps gives the equation for the overall reaction.arrow_forwardIn the presence of excess thiocyanate ion, SCN, the following reaction is first order in iron(III) ion, Fe3+; the rate constant is 1.27/s. Fe3+(aq)+SCN(aq)Fe(SCN)2+(aq) What is the half-life in seconds? How many seconds would be required for the initial concentration of Fe3+ to decrease to each of the following values: 25.0% left, 12.5% left, 6.25% left, 3.125% left? What is the relationship between these times and the half-life?arrow_forward
- One mechanism for the destruction of ozone in the upper atmosphere is a. Which species is a catalyst? b. Which species is an intermediate? c. Ea for the uncatalyzed reaction O3(g)+O(g)2O2(g) is 14.0 kJ. Ea. for the same reaction when catalyzed is 11.9 kJ. What is the ratio of the rate constant for the catalyzed reaction to that for the uncatalyzed reaction at 25C? Assume that the frequency factor A is the same for each reaction.arrow_forwardGaseous azomethane (CH3N2CH3) decomposes to ethane and nitrogen when heated: CH3N2CH3(g) CH3CH3(g) + N2(g) The decomposition of azomethane is a first-order reaction with k = 3.6 104 s1 at 600 K. (a) A sample of gaseous CH3N2CH3 is placed in a flask and heated at 600 K for 150 seconds. What fraction of the initial sample remains after this time? (b) How long must a sample be heated so that 99% of the sample has decomposed?arrow_forwardThe catalyzed decomposition of hydrogen peroxide is first-order in [H2O2]. It was found that the concentration of H2O2 decreased from 0.24 M to 0.060 M over a period of 282 minutes. What is the half-life of H2O2? What is the rate constant for this reaction? What is the initial rate of decomposition at the beginning of this experiment (when [H2O2] = 0.24 M)?arrow_forward
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