14.29 The decomposition reaction of N2O5 in carbon tetrachloride is N2O5→4 NO2 + O2. The rate law is first order in N2O5. At 64 °C the rate constant is 4.82 X 10-3 s-1. (a)Write the rate law for the reaction. (b) What is the rate of reaction when [N2O5] = 0.0240 M? (c) What happens to the rate when the concentration of N2O5 is doubled to 0.0480 M? (d) What happens to the rate when the concentration of N2O5 is halved to 0.0120 M?

[4] Consider the following mechanism for the reaction of nitric oxide and hydrogen: kı 2NO(g)+ H2(g) → N;O(g) + H¿O(g) slow k2 N,0(g) + H2(g) → N2(g) + H2O(g) fast (a) Write an equation for the overall reaction. (b) Write the theoretical rate law for the above mechanism. (c) Is a catalyst involved in the above mechanism? If so, what is it? (d) Are there any reaction intermediates? If so, list them.

The gas phase reaction between hydrogen and iodine is proposed to occur as follows: step 1: 12 →21 step 2: step 2 H₂ + 2 I (a) Identify the molecularity of each step in the mechanism. step 1 → 2 HI + (b) Write the equation for the net reaction. Use the smallest integer coefficients possible. If a box is not needed, leave it blank. + (c) Identify any intemediates in this mechanism. Intermediate: Enter formula. If none, leave box blank:

Assume that the formation of nitrogen dioxide, 2 NO(g) + 02(g) – 2 NO2(g) is an elementary reaction. (a) Write the rate law for this reaction. (Rate expressions take the general form: rate = k. [A]ª . [B]b.) chemPad О Help Greek - rate=k•[NO]2.[02] rate=k*[NO]^2*[O_2] Correct. (b) A sample of air at a certain temperature is contaminated with 1.9 ppm of NO by volume. Under these conditions, can the rate law be simplified? If so, write the simplified rate law. If not, repeat your answer from above. (Rate expressions take the general form: rate = k . [A]ª . [B]b. Use k' for the new rate constant as needed.) chemPad O Help Greek - rate=k':[NO]2 rate=k*[NO]^2 Correct. (c) Under the conditions described in (b), the half-life of the reaction has been estimated to be 6.7x103 min. What would the half-life be if the initial concentration of NO were 12.4 ppm? 4.0 |1030192 X min Supporting Materials Periodic Table Constants and E Supplemental Data

6. The rate constant for the reaction, 2 N₂O5 (g) → 4 NO2 (g) + O2 (g), doubles when the temperature is raised from 295.65 K to 300.62 K. (a) Determine the activation energy (in kJ/mol) for the reaction, assuming that the pre- exponential factor, A, in the Arrhenius equation is independent of temperature. (b) At what temperature would you predict this rate constant to increase by another factor of 10 relative to its value at 300.62 K?