Exam #2

Which rate law is termolecular? -rate = k[A][B] -rate = k[A]^2 -rate = k[A]^2[B] -rate = k[A] -rate = k[A][B][C][D]

What are the units of k in the following rate law? Rate = k[X][Y]^1/2

The combustion of ethylene proceeds by the reaction C2H4(g) + 3 O2(g) → 2 CO2(g) + 2 H2O(g) When the rate of disappearance of O2 is 0.13 M s^-1, the rate of appearance of CO2 is ________ M s^-1.

How many half-lives are required for the concentration of reactant to decrease to 12.5% of its original value?

What are the units of k in the following rate law? Rate = k[X][Y]^3

What is the rate law for the elementary step Cl + CO → ClCO?

What is the overall order of the following reaction, given the rate law? 2NO(g) + H2(g) → N2(g) + 2 H2O(g) Rate = k[NO]^2[H2]

Describe catalyst and its function. Check all that apply. -A catalyst is a substance that is not used up during a reaction. -A catalyst does not affect the products obtained in the reaction. -A catalyst is a substance that is used up during a reaction. -A catalyst changes the pathway of the reactants to products in a way that reduces the activation energy and speeds up the reaction. -A catalyst does not change the pathway of the reactants to products in a way that reduces the activation energy and lowers the speed of the reaction. -A catalyst affects the products obtained in the reaction.

The data below were collected for the following reaction: CH3Cl(g) + 3Cl2(g) → CCl4(g) + 3HCl(g) [CH3Cl](M) [Cl2](M) Initial rate (M/s) 0.050 0.050 0.014 0.100 0.050 0.029 0.100 0.100 0.041 0.200 0.200 0.115 -Choose an expression for the reaction rate law. -Calculate the value of the rate constant, k. -What is the overall order of the reaction?

Given the following proposed mechanism, predict the rate law for the overall reaction. A2 + 2 B → 2 AB (overall reaction) Mechanism A2 ⇌ 2 A fast A + B → AB slow

Given the following balanced equation, determine the rate of reaction with respect to [O2]. 2O3(g) → 3 O2(g)

A first-order reaction has a half-life of 27.8 s . How long does it take for the concentration of the reactant in the reaction to fall to one-eighth of its initial value?

Consider the equation for the decomposition of NO2, NO2(g)→NO(g)+O(g) The graph of 1/[NO2] versus time (s) is 1/[NO2] = 0.225x +100 Use the graph and the best fitting line to predict the concentration of NO2 at 1900 s.

Which statement is true regarding the function of a catalyst in a chemical reaction? -A catalyst provides an alternate mechanism for the reaction in which the rate-determining step has a higher activation energy. -Enzymes are biological catalysts capable of decreasing the rate of specific biochemical reactions by many orders of magnitude. -A catalyst is consumed by the reaction. -A catalyst increases the rate of a reaction.

The rate constant for a first-order reaction is 0.54 s^-1. What is the half-life of this reaction if the initial concentration is 0.27 M?

What happens to the concentrations of reactants and products during a chemical reaction?

A decomposition reaction has a half-life that is directly proportional to the initial concentration of the reactant. What is the order of the reaction?

For a particular reaction in which A → products, doubling the concentration of A causes the reaction rate to double. What is the order of the reaction?

The elementary reaction 2NO2(g) → 2 NO(g) + O2(g) is second order in NO2 and the rate constant at 720 K is 2.88 × 10^1 M^-1 s^-1. The reaction half-life at this temperature when [NO2]0 = 0.45 M is ________ s.

The reaction X → products is second order in X and has a rate constant of 0.035 M^−1 s^−1. If a reaction mixture is initially 0.80 M in X, what is the concentration of X after 120. seconds?

Reaction A and reaction B have identical frequency factors. However, reaction B has a higher activation energy than reaction A. Which reaction has a greater rate constant at room temperature?

The following reaction is first order in N2O5: N2O5(g) → NO3(g) + NO2(g) The rate constant for the reaction at a certain temperature is 0.053/s. -Calculate the rate of the reaction when [N2O5]= 5.2×10^−2 M. -What would the rate of the reaction be at the same concentration as in Part A if the reaction were zero order?

Consider the following reaction: O3(g)→O2(g)+O(g) Using the results of the Arrhenius analysis (Ea=93.1 kJ/mol and A=4.36×1011 M⋅s^−1), predict the rate constant at 303 K .

Given the following rate law, how does the rate of reaction change if the concentration of Y is doubled? Rate = k[X][Y]^2

Determine the rate law and the value of k for the following reaction using the data provided. 2N2O5(g) → 4NO2(g) + O2(g) [N2O5]i (M) Initial Rate (M/s) 0.093 4.84 × 10^-4 0.186 9.67 × 10^-4 0.279 1.45 × 10^-3

Which of the following represents the integrated rate law for a first-order reaction? -1/[A]o − 1/[A]t = −kt -ln(k1/k2) = ln(Ea/R)(1T) + lnA -k = Ae^(Ea/RT) -[A]o − [A]t= −kt -ln([A]t/[A]o) = −kt

A particular first-order reaction has a rate constant of 1.35 × 102 s^-1 at 25.0°C. What is the magnitude of k at 75.0°C if Ea = 64.5 kJ/mol?

The reaction between nitrogen dioxide and carbon monoxide is NO2(g)+CO(g)→NO(g)+CO2(g) The rate constant at 701 K is measured as 2.57 M^−1⋅s^−1 and that at 895 K is measured as 567 M^−1⋅s^−1. Use the value of the activation energy (Ea=1.50×10^2 kJ/mol) and the given rate constant of the reaction at either of the two temperatures to predict the rate constant at 495 K.

The rate constant of a reaction is measured at different temperatures. A plot of the natural log of the rate constant as a function of the inverse of the temperature (in kelvins) yields a straight line with a slope of −8.35 × 10^3 K. What is the activation energy (Ea) for the reaction?

The mechanism shown here is proposed for the gas phase reaction, O2 + 2NO(g)→2NO2. 2NO2NO ⇌k1/k-1 N2O2 Fast O2+N2O2→2NO2 Slow What rate law does the mechanism predict?

The following reaction was monitored as a function of time: AB→A+B A plot of 1/[AB] versus time yields a straight line with slope 5.9×10^−2 (M⋅s)^−1. -What is the value of the rate constant (k) for this reaction at this temperature? -Write the rate law for the reaction. -What is the half-life when the initial concentration is 0.51 M? -If the initial concentration of AB is 0.220 M, and the reaction mixture initially contains no products, what are the concentrations of A and B after 80 s?

Identify an homogeneous catalyst. -Pd with methane -H2SO4 with concentrated HCl -SO2 over vanadium (V) oxide -Pt in H2 gas -N2 catalyzed by Fe