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Identify the reaction intermediate(s) in the reaction mechanism shown. (CH3)3C-OH Br- (CH3)3C+ (CH3)3C-OH2+ (CH3)3C-Br

(CH3)3C+ (CH3)3C-OH2+

Every chemical reaction proceeds through a high-energy unstable species as reactants are converted to products and bonds are in the process of being formed and/or broken. This unstable species is called a(n) ______ complex or _______ state.

activated, transition

Collision theory states that particles will react when they _______ with each other. For a reaction to be successful, the particles must have enough _________ energy.

collide, kinetic

Reaction rates are expressed as the change in ________ , over a period of _______

concentration, time

True or false: Based on the balanced equation N2 (g) + 3H2 (g) → 2NH3 (g), the rate law is given by rate = k[N2][H2]3.

false

An increase in temperature causes the reaction rate to increase. At a higher temperature the average _______ energy of the particles is greater, and the fraction of particles with enough energy to exceed the _________ energy is greater.

kinetic, activation

The ________ constant, given the symbol k, expresses the proportionality between reactant concentration and reaction rate for a given reaction. The value of k is constant at constant _______

rate, temperature

The Arrhenius equation relates the rate constant of a reaction to ______. Select all the options that would complete this sentence correctly. the frequency of collisions between particles reactant concentrations the activation energy the reaction order the absolute temperature

the frequency of collisions between particles the activation energy the absolute temperature

Which of the following plots will give a straight line for a reaction that follows second-order kinetics? The reaction is represented by A → products. 1/[A] versus time ln[A] versus time [A] versus time 1/ln[A] versus time

1/[A] versus time

Which of the following conditions must be satisfied for a collision between reactants to be effective? Select all that apply.

Enough energy to overcome Ea Appropriate molecular orientation

Which of the following the statements correctly relate experimental observations with reaction order? Select all that apply. (Assume A is a reactant in all cases.) If [A] is doubled and the reaction rate does not change, the reaction is first order with respect to A. If a reaction is second order with respect to A, the rate will increase by a factor of 6 if [A] is increased to 3 times its original value. If [A] is doubled and the reaction rate increases by a factor of 4, the reaction is second order with respect to A. If [A] is decreased to one-half of its original value and the reaction rate is halved, the reaction is first order with respect to A.

If [A] is doubled and the reaction rate increases by a factor of 4, the reaction is second order with respect to A. If [A] is decreased to one-half of its original value and the reaction rate is halved, the reaction is first order with respect to A.

Which of the following the statements correctly relate experimental observations with reaction order? Select all that apply. (Assume A is a reactant in all cases.) If a reaction is second order with respect to A, the rate will increase by a factor of 6 if [A] is increased to 3 times its original value. If [A] is doubled and the reaction rate does not change, the reaction is first order with respect to A. If [A] is doubled and the reaction rate increases by a factor of 4, the reaction is second order with respect to A. If [A] is decreased to one-half of its original value and the reaction rate is halved, the reaction is first order with respect to A.

If [A] is doubled and the reaction rate increases by a factor of 4, the reaction is second order with respect to A. If [A] is decreased to one-half of its original value and the reaction rate is halved, the reaction is first order with respect to A.

Which of the following options correctly interpret the rate law rate = k[H2][NO]2? Select all that apply. The overall order of reaction is 2. If [NO] is doubled while [H2] remains the same, the reaction will occur 4 times faster. The reaction is second order with respect to NO. If [H2] is doubled while [NO] remains the same, the reaction rate will not change. If both [H2] and [NO] are doubled, the reaction rate will occur 6 times faster.

If [NO] is doubled while [H2] remains the same, the reaction will occur 4 times faster. The reaction is second order with respect to NO.

Which of the following elementary reactions are unimolecular? Select all that apply. N2O4 (g) → 2NO2 (g) PCl5 (g) → PCl3 (g) + Cl2 (g) 2CO (g) + O2 (g) → 2CO2 (g) 2HI (g) → H2 (g) + I2 (g) 2NO (g) → N2O2 (g)

N2O4 (g) → 2NO2 (g) PCl5 (g) → PCl3 (g) + Cl2 (g)

Which of the following conditions must be fulfilled in order to calculate reaction rate using change in pressure over time rather than change in concentration? Select all that apply. One reactant or product must be a gas. The temperature at which the reaction is carried out must be known. There must be no gaseous reactants present. All reactants and products must be gases.

One reactant or product must be a gas. The temperature at which the reaction is carried out must be known.

Which of the following are examples of heterogeneous catalysis? Select all that apply. Oxides of nitrogen are converted to O2 and N2 in a catalytic converter. Liquid petroleum products react with hydrogen gas on the surface of platinum metal. The decomposition of aqueous hydrogen peroxide to water is catalyzed by a solution of sodium iodide.

Oxides of nitrogen are converted to O2 and N2 in a catalytic converter. Liquid petroleum products react with hydrogen gas on the surface of platinum metal.

Select the statements that correctly describe the kinetics of an elementary reaction. The elementary reaction 2HI (g) → H2 (g) + I2 (g) follows second-order kinetics. The rate law for an elementary step can be deduced from its balanced chemical equation. The reaction order for an elementary reaction must be determined by experiment in the same way as for any other chemical reaction. For the elementary reaction H2 (g) → 2H (g), reaction rate = k[H]2. For an elementary reaction, reaction order equals molecularity.

The elementary reaction 2HI (g) → H2 (g) + I2 (g) follows second-order kinetics. The rate law for an elementary step can be deduced from its balanced chemical equation. For an elementary reaction, reaction order equals molecularity.

Select all the options that correctly describe how this mechanism meets, or does not meet, the criteria for validity. The mechanism has too many steps to be reasonable. The rate law does not take into account that there are 4HBr molecules involved in the reaction. The rate law is consistent with the proposed mechanism. The elementary steps are logical and physically reasonable. The elementary steps do not add up to the overall equation.

The rate law is consistent with the proposed mechanism. The elementary steps are logical and physically reasonable.

Which of the following statements correctly describe how a rate law is determined? Select all that apply. The rate law is determined by measuring the initial reaction rate for different reactant concentrations. The rate law is determined by measuring the reaction rate for different product concentrations. The rate law is determined from the balanced chemical equation. The value of k can be calculated from a single experiment once the reaction orders are known. If there is more than one reactant present the reaction orders will usually be determined individually.

The rate law is determined by measuring the initial reaction rate for different reactant concentrations. The rate law is determined by measuring the reaction rate for different product concentrations. The value of k can be calculated from a single experiment once the reaction orders are known. If there is more than one reactant present the reaction orders will usually be determined individually.

Select all the options that correctly interpret the potential energy profile shown. Points b and d represent reaction intermediates. The first step of the reaction has a higher activation energy. The second step of this reaction is rate-determining. This reaction involves 2 steps. The overall reaction is endothermic.

The second step of this reaction is rate-determining. This reaction involves 2 steps. The overall reaction is endothermic.

Which of the following statements correctly describe catalysts? Select all that apply. Catalysts are added in nonstoichiometric amounts and are consumed over the course of a reaction. A catalyzed reaction has a higher yield than an uncatalyzed reaction. Catalysts only increase k of the forward reaction, not the reverse reaction. Catalysts provide a different mechanism for the reaction. Catalysts lower the activation energy of the rate-determining step in the reaction.

Catalysts provide a different mechanism for the reaction. Catalysts lower the activation energy of the rate-determining step in the reaction.

Which of the following statements correctly describe chemical kinetics? Select all that apply. Chemical kinetics is the study of reaction rates. Chemical kinetics focuses on theoretical aspects of reaction rates and does not involve any measurement. Chemical kinetics measures how fast reactants are converted into products. Chemical kinetics is chiefly concerned with the overall amount of energy absorbed or released in a reaction. Chemical kinetics describes chemical reactions using collision theory.

Chemical kinetics is the study of reaction rates. Chemical kinetics measures how fast reactants are converted into products. Chemical kinetics describes chemical reactions using collision theory.

Which of the following options correctly describe the principles of collision theory? Select all that apply. Collision theory states that in general particles must collide in order to react. Reaction rate is directly proportional to the number of collisions per second. When particles collide, some of their kinetic energy is converted to vibrational energy. Collision theory states that when particles collide with the walls of the container they are able to react. All collisions between particles will lead to a reaction.

Collision theory states that in general particles must collide in order to react. Reaction rate is directly proportional to the number of collisions per second. When particles collide, some of their kinetic energy is converted to vibrational energy.

Select all the statements that correctly describe how a chemical reaction is affected by an increase in temperature. Collisions between reacting particles are more frequent. The activation energy decreases. The reaction rate increases. The average collision energy increases. The activation energy increases.

Collisions between reacting particles are more frequent. The reaction rate increases. The average collision energy increases.

Which of the following criteria must be met for a reaction mechanism to be considered valid? Select all that apply. The elementary steps must add up to the overall balanced reaction. Each elementary step should involve only one reacting species. The rate law for the rate-determining step must correlate with the experimentally determined rate law. The mechanism must contain the smallest number of elementary steps possible.

The elementary steps must add up to the overall balanced reaction. The rate law for the rate-determining step must correlate with the experimentally determined rate law.

A chemical reaction occurs in three elementary steps and is exothermic overall. The first step is the slowest step. Select all the statements that correctly describe the potential energy profile for this reaction. The energy of the products will be lower than the energy of the reactants. Each peak in the energy profile represents the reaction intermediate for an elementary step. There will be three peaks in the energy profile. The second peak in the energy profile will be the highest.

The energy of the products will be lower than the energy of the reactants. There will be three peaks in the energy profile.

The order of a reaction and its rate constant can be determined graphically. Select all the statements that correctly describe this process. The reaction order is determined from a direct plot of [A] versus time. The function of [A] versus time that gives a straight line plot indicates the reaction order. The rate constant is related to the slope of the straight line obtained. The order of the reaction equals the value of the y intercept of the straight line.

The function of [A] versus time that gives a straight line plot indicates the reaction order. The rate constant is related to the slope of the straight line obtained.

Which of the following statements correctly describe the half-life of a reaction? Select all that apply. The half-life of a reaction is always a constant value. The half-life of a reaction is the time it takes for [A]0 to drop to half its original value. A chemical reaction is complete after two half-lives have passed. The half-life of a first-order reaction is independent of the initial concentration. The half-life of a reaction is related to its rate constant.

The half-life of a reaction is the time it takes for [A]0 to drop to half its original value. The half-life of a first-order reaction is independent of the initial concentration. The half-life of a reaction is related to its rate constant.

Which of the following are described by a reaction mechanism? Select all that apply. The identities of any reaction intermediates An explanation of the way in which the individual reactants are transformed to products The sequence of individual steps that make up the reaction The reaction orders and rate equation for the reaction The overall balanced chemical equation

The identities of any reaction intermediates An explanation of the way in which the individual reactants are transformed to products The sequence of individual steps that make up the reaction The overall balanced chemical equation

Which of the following statements correctly describe average rate, instantaneous rate, and initial rate? Select all that apply. The initial rate is an instantaneous rate at t = 0. The initial rate is the average instantaneous rate. The average rate is an average of instantaneous rates for a given period of time. There is no difference between instantaneous and initial rates. The average rate is the initial rate when reactants are mixed.

The initial rate is an instantaneous rate at t = 0. The average rate is an average of instantaneous rates for a given period of time.

Select all the statements that correctly describe the instantaneous reaction rate. Instantaneous rate = k x average rate Instantaneous rate, unlike average rate, does not change over time. The instantaneous reaction rate is proportional to reactant concentration. Instantaneous rate is calculated by finding the slope of a tangent to the curve of concentration versus time at any point on the curve. Instantaneous rate is calculated by finding the average change in reactant concentration over a specific time interval.

The instantaneous reaction rate is proportional to reactant concentration. Instantaneous rate is calculated by finding the slope of a tangent to the curve of concentration versus time at any point on the curve.

The order of a reaction and its rate constant can be determined graphically. Select all the statements that correctly describe this process. The reaction order is determined from a direct plot of [A] versus time. The rate constant is related to the slope of the straight line obtained. The order of the reaction equals the value of the y intercept of the straight line. The function of [A] versus time that gives a straight line plot indicates the reaction order.

The order of the reaction equals the value of the y intercept of the straight line. The function of [A] versus time that gives a straight line plot indicates the reaction order.

Select all the statements that correctly describe a zeroth-order reaction. The reaction is represented by A → products. The integrated rate law for a zeroth-order reaction is given by ln[A]t = -kt + ln[A]0 The rate constant of a zeroth-order reaction is equal to the reaction rate. For a zeroth-order reaction, a plot of [A]t versus time will give a straight line. The rate of a zeroth-order reaction is independent of reactant concentration.

The rate constant of a zeroth-order reaction is equal to the reaction rate. For a zeroth-order reaction, a plot of [A]t versus time will give a straight line. The rate of a zeroth-order reaction is independent of reactant concentration.

Which of the following statements correctly describe the rate constant k for a reaction? Select all that apply. The rate constant relates reaction rate to reactant concentration. The value of k is equal to the slope of a tangent to the curve obtained by plotting [reactant] versus time. The value of k changes as [reactant] changes. The rate constant has a constant value for a given reaction at a constant temperature.

The rate constant relates reaction rate to reactant concentration. The rate constant has a constant value for a given reaction at a constant temperature.

Which of the following statements correctly describe how a rate law is determined? Select all that apply. The rate law is determined from the balanced chemical equation. If there is more than one reactant present the reaction orders will usually be determined individually. The rate law is determined by measuring the initial reaction rate for different reactant concentrations. The rate law is determined by measuring the reaction rate for different product concentrations. The value of k can be calculated from a single experiment once the reaction orders are known.

The rate law is determined from the balanced chemical equation. If there is more than one reactant present the reaction orders will usually be determined individually. The rate law is determined by measuring the initial reaction rate for different reactant concentrations. The value of k can be calculated from a single experiment once the reaction orders are known.

Which of the following statements correctly describe a rate law for a reaction? Select all that apply. (Assume that the reaction is not reversible to any appreciable extent.) The rate law relates the rate of reaction to the concentrations of the reactants. The form of the rate law will change if the temperature changes. The rate law includes the rate constant for the reaction. The rate law relates the rate of reaction to the concentration of the products. The rate law relates the value of the rate constant, k, to reaction time.

The rate law relates the rate of reaction to the concentrations of the reactants. The rate law includes the rate constant for the reaction.

Which of the following factors are affected by an increase in reactant concentration? Select all that apply. The rate of reaction The energy of the reactants The average energy of reactant collisions The number of reactant particles in a given volume The number of reactant collisions

The rate of reaction The number of reactant particles in a given volume The number of reactant collisions

Select all the statements that describe an integrated rate law. The reactant concentration at any time in the reaction can be determined from the integrated rate law. An integrated rate law has the general form k[A]x[B]y where A and B are reactants. The value of the reaction constant, k, can be determined using an integrated rate law. An integrated rate law includes time as a variable. Reaction orders do not affect the form of the integrated rate law.

The reactant concentration at any time in the reaction can be determined from the integrated rate law. The value of the reaction constant, k, can be determined using an integrated rate law. An integrated rate law includes time as a variable.

Which of the following statements correctly describe the straight-line plot obtained from concentration and time data for the first-order reaction A → products? Select all that apply. The straight line is obtained by plotting ln[A] versus time. The straight line is obtained by plotting [A] versus time. The rate constant for the reaction is related to the slope of the straight line. The slope of the line is negative. The value of the y intercept is zero.

The straight line is obtained by plotting ln[A] versus time. The rate constant for the reaction is related to the slope of the straight line. The slope of the line is negative.

Which of the following statements correctly describe the transition state of a reaction? Select all that apply. The energy required to form the transition state is the enthalpy change of the reaction (ΔH). The transition state only exists at the instant of highest potential energy in the reaction. The transition state species is either the reactant or product depending on the reaction. The transition state species is highly unstable.

The transition state only exists at the instant of highest potential energy in the reaction. The transition state species is highly unstable.

Select all the options that correctly describe the straight-line plot obtained for rate constant and temperature data. The value of k can be determined from the slope of the line. The straight line is obtained by plotting k versus 1/[T] The activation energy for the reaction is equal to the value of the y intercept. The values plotted on the x axis are given by 1/[T] where T is the absolute temperature. The activation energy for the reaction can be determined from the slope.

The values plotted on the x axis are given by 1/[T] where T is the absolute temperature. The activation energy for the reaction can be determined from the slope.

Which question(s) can be answered from an integrated rate law that cannot be answered by other forms of the rate law? Select all that apply. What is [A] after y minutes of the reaction? What is the rate constant? How long will it take to use up x moles per liter of A? What is the order of the reaction?

What is [A] after y minutes of the reaction? How long will it take to use up x moles per liter of A?