Chapter 14 Problems

Calculate the rate constant for a reaction at 75°C that has an activation energy of 80.2 kJ/mol and a frequency factor of 3.58 × 1011 s−1.

.332

For the second-order reaction 2 A → B + C, 4.58 hours are required for the concentration of A to decrease from an initial concentration of 0.398 M to 0.183 M at 40°C. Calculate the rate constant for this reaction at 40°C.

.645

The half-life of a second-order decomposition reaction is 278 s when the initial concentration of the reactant is 0.059 M. Calculate the rate constant for this reaction.

6.10 x 10^-2

Use the energy diagrams to determine the activation energy, Ea, and enthalpy of reaction, ΔH, for each reaction.

Reaction A Ea: 100 kJ ΔH: -50 kJ Reaction B Ea: 250 kJ ΔH: 150 kJ

Based on the energy diagrams in the previous problem, predict which reaction proceeds at the higher rate or whether they proceed at the same rate. Explain the reasoning behind your answer.

Reaction A because the Ea is lower than reaction B

The decomposition of sulfuryl chloride, SO2Cl2, is a first-order process with a rate constant of 4.50 × 10−2 s−1 at 660 K. SO2Cl2(g)→SO2(g)+Cl2(g) The initial concentration of SO2Cl2 is 0.693 M. a) Calculate the concentration of SO2Cl2 after 24.5 s. b) How many seconds does it take for the concentration of SO2Cl2 to drop to 3.59 × 10−3 M?

a) .230 b) 117 s

The decomposition reaction A → B + C is a second-order process with a rate constant of 6.92 × 10−3 M−1·s−1. The initial concentration of A is 0.0248 M. a) Calculate the concentration of A after 78.9 min. b) How many minutes does it take for the concentration of A to drop to 4.28 × 10−3 M?

a) .296 b) 4.66 x 10^4

For the reaction 3 A + B → 2 C + 2 D, the rate of change of reactant A is determined to be −3.56×10^−3M⋅s−1. a) What is the rate of the reaction at this point? b) What is the rate of change of reactant B? c) What is the rate of change of product D?

a) 1.19 x10^-3 b) -1.19 x 10^-3 c) 2.37 x 10^-3

Concentration and time data for the reaction A → B are given below. a) Concentration and time data for the reaction A → B are given below. b) Calculate the instantaneous rate of change at t = 40.0 s.

a) 6.35 x 10^-4 b) (.07-.0.01)/100 = 6 x 10^-4

The reaction 2 A + 2 B → products has a rate law of rate = k[A]. a) What is the order of the reaction with respect to A? b) What is the order of the reaction with respect to B? c) What is the overall reaction order?

a) First b) Zero c) First

The following mechanism has been proposed for the formation of HI(g), which has a rate law of rate = k[H2][I2]. Step1:I2(g)⇋2I(g) (fast, equilibrium) Step2:H2(g)+2I(g)→2HI(g) (slow) a) Write the overall balanced reaction. b) Show that the proposed mechanism is consistent with the rate law. c) Express the overall rate constant k in terms of the rate constants for the elementary reactions.

a) H2(g) + I2(g) --> 2HI(g) b) 2I(g) is an intermediate so it doesn't show up in the overall rate law. It is equal to I2(g) so I2(g) shows up instead of 2I(g) c) idk

For the generic reaction A → B, state whether the following changes will result in an increase in the reaction rate, a decrease in the reaction rate, or whether the reaction rate will be unaffected. a) increasing the concentration of A b) decreasing the temperature c) adding a catalyst d) increasing the concentration of B

a) Increase b) Decrease c) Increase d) Unaffected

The decomposition of nitramide, NH2NO2, in aqueous solution is thought to occur through the following two-step mechanism. Step1:NH2NO2(aq)+OH−(aq)→NHNO−2(aq)+H2O(l) Step2:NHNO−2(aq)→N2O(g)+OH−(aq) a) Write the balanced equation for the overall reaction. b) Identify any intermediates and catalysts.

a) NH2NO2(aq) --> N2O(g) + H2O(l) b) Intermediate: NHNO2^- Catalyst: OH^-

The following initial rate data at 600 K were collected for the reaction H2(g)+I2(g)→2 HI(g) a) Write the rate law. b) Calculate the rate constant. c) What is the rate when [H2] = 0.250 M and [I2] = 0.800 M?

a) Rate = k[H2][I2] b) k = 4.4 x 10^-4 c) 8.8 x 10^-5

Write the rate law and identify the molecularity of the following elementary reactions. a) 2 NO2(g)→NO3(g)+NO(g) b) SO2Cl2(g)→SO2(g)+Cl2(g) c) Cl(g)+Cl(g)+N2(g)→Cl2(g)+N2(g) d) O3(g)+Cl(g)→O2(g)+ClO(g)

a) [NO2]^2 b) [SO2Cl2] c) [Cl]^2[N2] d) [O3][Cl]