Suppose that a catalyst lowers the activation barrier of a reaction from 127 kJ/mol to 51 kJ/mol . By what factor would you expect the reaction rate to increase at 25 ∘C? (Assume that the frequency factors for the catalyzed and uncatalyzed reactions are identical.)

Can a reaction mechanism ever be proven correct? Can it be proven incorrect?

Bacteria cause milk to go sour by generating lactic acid. Devise an experiment that could measure the activation energy for the production of lactic acid by bacteria in milk. Describe how your experiment will provide the information you need to determine this value. What assumptions must be made about this reaction?

The reaction NO(g) + O,(g) — NO,(g) + 0(g) plays a role in the formation of nitrogen dioxide in automobile engines. Suppose that a series of experiments measured the rate of this reaction at 500 K and produced the following data; [NO] (mol L ’) [OJ (mol L 1) Rate = -A[NO]/Af (mol L_1 s-1) 0.002 0.005 8.0 X 10"'7 0.002 0.010 1.6 X 10-'6 0.006 0.005 2.4 X IO-'6 Derive a rate law for the reaction and determine the value of the rate constant.

(Section 11-5) A rule of thumb is that for a typical reaction, if concentrations are unchanged, a 10-K rise in temperature increases the reaction rate by two to four times. Use an average increase of three times to answer the questions below. (a) What is the approximate activation energy of a typical chemical reaction at 298 K? (b) If a catalyst increases a chemical reactions rate by providing a mechanism that has a lower activation energy, then what change do you expect a 10-K increase in temperature to make in the rate of a reaction whose uncatalyzed activation energy of 75 kJ/mol has been lowered to one half this value (at 298 K) by addition of a catalyst?

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?

11.35 For the reaction 2 NO(g) + 2 H?(g) — N,(g) + 2 H,O(g) at 1100°C, the following data have been obtained: [NOJ [HJ Rate = A(N2]/At (mol L~1) (mol L_1) (mol L-1 s_1) 5.0 X 10’1 0.32 0.012 1.0 X 10~’ 0.32 0.048 1.0 X 10"2 0.64 0.096 Derive a rate law for the reaction and determine the value of the rate constant.

. Account for the increase in reaction rate brought about by a catalyst.

Define stability from both a kinetic and thermodynamic perspective. Give examples to show the differences in these concepts.

The dissociation of N2O4 into NO2, N2O4(g)2NO2(g) is believed to occur in one step Obtain the concentration of N2O4 in terms of the concentration of NO2 and the rate constants for the forward and reverse reactions, when the reactions have come to equilibrium.