Chemical Kinetics Practice Test

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• Which relationship links the rate constant k to the slope m for zero-order or first-order plots?
• In a competing pathway where A can form P via k1 and Q via k2, what is k_obs in terms of k1 and k2?
• Provide the general form of a second-order rate law for a reaction involving two different reactants A and B and explain how to determine m and n.
• What describes a substance that initiates or accelerates a chemical reaction without itself being consumed?
• How does the zero-order half-life depend on the concentration [A]?
• How do you determine the overall order of a reaction from its rate law?
• For a rate law that is first order in A and first order in B, with B held constant, how does the rate change when A is doubled?
• Which plot yields a straight line for a first-order reaction?
• Explain why the experimentally determined rate law may differ from the stoichiometric coefficients in the overall balanced equation.
• What is instantaneous rate?
• Which change can increase the frequency of productive collisions by altering the phase of reacting species?
• Derive Ea from rate constants measured at two temperatures, given k1 at T1 and k2 at T2
• Explain why an overall rate law may not reflect a single elementary step in a multi-step mechanism.
• Which plot would be linear for a first-order reaction in A → products?
• Which expression represents the integrated rate law for a first-order reaction?
• Do rate laws always reflect the stoichiometric coefficients?
• State the Arrhenius equation and identify the physical meaning of each parameter.
• Which statement correctly distinguishes true first-order from pseudo-first-order?
• Which statement correctly pairs zero- and first-order half-life expressions?
• What is the difference between a zero-order decay and a pseudo-zero-order scenario?
• In a multi-step mechanism, the overall rate is determined by
• How are gas-phase reaction rates commonly expressed when using pressures instead of concentrations?
• What is average rate?
• If a reaction rate equals k [A]^m [B]^n, what is the overall order of the reaction?
• For a second-order reaction, which equation represents the straight-line form on a plot of 1/[A] versus time?
• Using two temperatures T1 = 300 K and T2 = 320 K with k2/k1 = 4, estimate Ea.
• For a first-order decay with k = 0.50 h^-1 and [A]0 = 1.0 M, what is [A] after 3 h?
• What is the process used to determine the form of the rate law and the powers for each reactant?
• For a first-order reaction, which of the following is the correct integrated rate law and half-life expression?
• Which of the following correctly lists the typical units of the rate constant k for zero-, first-, and second-order reactions?
• Which of the following gives the correct units for k in a second-order reaction?
• For a zero-order reaction, which plot yields a straight line?
• Which statement correctly contrasts the differential rate law and the integrated rate law?
• Which expression is an integrated rate law for a first-order reaction?
• Which term means a process that releases heat?
• What is the half-life expression for a zero-order reaction?
• Consider a mechanism in which A ⇌ I (fast equilibrium) is followed by I → P (slow). What is the overall rate law expressed in terms of [A]?
• What is the integrated rate law for a second-order reaction with rate = k[A]^2?
• For a reaction with two reactants A and B, if m = 1 and n = 0, the rate depends on which component?
• Which statement best describes how temperature affects collision theory?
• What describes how the rate of reaction depends on the concentration?
• What is the rate law for a zero-order reaction?
• General form for rate law for aA → products
• What is the sum of the orders for the various reactants?
• Which factor increases the likelihood of productive collisions by exposing more surface area?
• For the rate law rate = k [A]^2 [B], by what factor does the rate increase if [A] is tripled and [B] is doubled?
• The slope of the linear plots for zero-order and first-order kinetics is typically:
• How does the steady-state approximation lead to the Michaelis-Menten equation for enzyme kinetics?
• For a zero-order reaction, which option correctly gives the integrated rate law and half-life expression?
• In a bimolecular reaction A + B -> products with B in large excess so rate ≈ k_obs[A], if k = 2.0 M^-1 s^-1 and [B]0 = 0.50 M, what is k_obs?
• For rate law rate = k [A][B], overall order and how to determine exponents?
• Provide an example of a first-order process and describe how its half-life changes with temperature.
• If the equilibrium constant K for A ⇌ B is greater than 1, which statement describes the equilibrium concentrations?
• What is the effect of lowering the activation energy Ea on the rate of a catalyzed reaction at a fixed temperature?
• Which parameter is constant for a given temperature in rate law rate = k[A]^m?
• In a zero-order reaction, how does the half-life change with increasing initial concentration [A]0 if k is constant?
• In the second-order plot, what is the y-intercept of the straight line 1/[A] versus time?
• In a reaction with rate law v = k[A], what is the order of the reaction?
• In the initial-rate method for determining reaction order, which plot is used to deduce the order with respect to a particular reactant?
• What is a clock reaction and how can it be used to study kinetics?
• Which statement describes the state of ΔG and Keq when a catalyst is used?
• Lineweaver-Burk plot is used to linearize the Michaelis-Menten equation. Which quantities are plotted?
• For a reversible reaction A ⇌ B with forward rate kf[A] and backward rate kb[B], which statement is true at equilibrium? (Choose the correct relation at equilibrium.)
• Why is the half-life for a first-order reaction independent of the initial concentration?
• Which of the following best illustrates a bimolecular elementary step?
• What is the sign of the slope m for a first-order plot of ln[A] versus time?
• For a second-order reaction with rate = k[A]^2 and [A]0 = 0.100 M, k = 0.200 M^-1 s^-1, what is t1/2?
• What does the Arrhenius pre-exponential factor A mainly reflect?
• What is the reaction rate?
• The activated complex is best described as:
• What is the half-life of the first-order decay with k = 0.231 h^-1?
• For an elementary reaction A + B -> products, what is the form of its rate law and its overall order?
• Which expression describes the first-order plot that yields a straight line?
• According to transition state theory, which description best matches the 'transition state'?
• Termolecular reaction
• In Michaelis-Menten kinetics, Km equals (k-1 + k2)/k1. Which statement correctly reflects Km?
• In an Arrhenius plot, what does the intercept ln A represent?
• In Michaelis-Menten kinetics, what happens to v as [S] becomes very large?
• Increasing temperature generally affects the rate of a reaction by
• What is the rate constant?
• Why do rate constants depend on temperature?
• At very high [S], what happens to the rate v in Michaelis-Menten kinetics?
• How does a catalyst influence the activation energy and rate constant without changing ΔG or Keq?
• What is the activated complex in a chemical reaction?
• Define a pseudo-first-order reaction and give the relation between k' and k.
• What is the general relationship between collision frequency and reaction rate in collision theory?
• What is the typical upper limit for bimolecular rate constants in solution at room temperature, indicating diffusion control?
• In a multi-step mechanism, which statement best explains why the overall rate may be controlled by steps other than the stoichiometry of the overall reaction?
• Collision theory suggests what determines the rate of a reaction?
• What is an energy diagram?
• What is chemical kinetics?
• In collision theory, collisions are either effective or noneffective. Which option reflects that?
• What is the rate-determining step in a multi-step mechanism?
• Which statement best describes a reaction intermediate?
• Which statement best defines the rate of a chemical reaction?
• Which differential equation correctly describes the rate of change of B in a consecutive A → B → C mechanism?
• Which statement best distinguishes elementary steps from the overall reaction mechanism and explains why the observed rate law may differ from the overall stoichiometry?
• In a rate law rate = k[A]^m[B]^n, what is the overall order?
• Which expression describes the zero-order concentration change over time?
• What is the rate law for a first-order reaction?
• If a reaction is first-order in A and zero-order in B, write the rate law and the overall order.
• Which of the following can act to alter the rate without being consumed in the overall reaction?
• An elementary reaction is defined as
• In a second-order reaction with rate law rate = k[A]^2, the half-life is t1/2 = ?
• For a simple reversible reaction A ⇌ B, how is the equilibrium constant related to the forward and reverse rate constants for A ⇌ B?
• The natural logarithm is the inverse function of which exponential function?
• How does physical state affect rate?
• If doubling [A] while [B] is constant causes the initial rate to increase by a factor of 4, what is the order with respect to A?
• What best describes the reaction mechanism?
• Molecularity is
• If rate = k [A]^2 [B], what is the rate factor when you double [A] and [B] simultaneously?
• Which of the following statements describes how a clock reaction can be used to infer reaction orders?
• What is the half-life expression for a first-order reaction?
• How do homogeneous and heterogeneous catalysts differ in their influence on Ea and the reaction rate?
• According to the Arrhenius equation, if the activation energy Ea is lowered at the same temperature, what happens to the rate constant k?
• In a chain reaction, what role does a chain carrier play?
• What is the kinetic isotope effect and what does it reveal about the rate-determining step?
• What is a species that forms during a reaction but is consumed along the process?
• Bimolecular reaction
• In the classic enzyme-catalyzed mechanism, the Michaelis-Menten rate law is v = (Vmax [S])/(Km + [S]); what are Vmax and Km in terms of the rate constants and enzyme concentration?
• Which type of collision leads to a reaction?
• Which experimental method is commonly used to determine the rate law by varying one reactant at a time and measuring initial rates?
• Which of the following is a factor that can affect the rate of a chemical reaction?
• What does the half-life of a zero-order reaction depend on?
• Activation energy
• What is the term for the curve depicting potential energy versus reaction progress?
• Unimolecular reaction involves
• In collision theory, what does proper orientation mean for reactive collisions?
• What assumption is made about the concentration of the enzyme-substrate complex [ES] in the steady-state approximation?
• Write the differential equations for a consecutive first-order mechanism A → B → C with rate constants k1 and k2.
• Which term means a process that absorbs heat?
• Which statement best describes the rate constant?
• How do competitive and noncompetitive inhibitors alter Km and Vmax?
• How would you distinguish a second-order reaction in one reactant from a second-order reaction in two different reactants?
• For a first-order reaction, what happens to the rate when the concentration doubles?
• In the mechanism A ⇌ I (fast equilibrium) followed by I -> P (slow), which step is rate-determining?
• In a bimolecular reaction with B in large excess, which expression defines k_obs?
• Define activation energy Ea and explain its relation to the transition state.
• For a fast pre-equilibrium where Step 1 is A ⇌ I and Step 2 I → P is slow, the rate law can often be expressed in terms of the equilibrium constant K1 and a rate constant. Which expression is correct?
• What shows how the concentrations of species in the reaction depend on time?
• Collision energy requirement.
• If the rate-determining step is unimolecular, what is the apparent order of the reaction?
• What is the purpose of the pre-equilibrium approximation?
• In the rate law, what does the exponent for a reactant represent?
• Which term describes the exponent to which a reactant concentration is raised in the rate law?
• What is the sign of the slope m for a zero-order plot of concentration versus time?
• Using the Arrhenius equation, calculate k for A = 1.0×10^13 s^-1, Ea = 50 kJ/mol, T = 298 K. (R = 8.314 J/mol·K)
• In a competing pathway scenario where A can form P via k1 and Q via k2, what is the observed rate of disappearance of A?
• What does the pre-exponential factor A depend on in terms of molecular motion and orientation?
• In Michaelis-Menten kinetics, what does Km represent?
• According to collision theory, which conditions must be satisfied for a reaction to occur?
• What is the definition of integration?
• If [B] is held constant and [A] is doubled in a rate law rate = k [A]^2 [B], by what factor does the rate change?
• If a plot of ln(k) versus 1/T yields a line with slope -Ea/R and the slope is -6.0 x 10^3 K, what is Ea approximately?
• For first-order decay with k = 0.231 h^-1 and initial concentration [A]0 = 0.100 M, what is [A] after 3 h?
• In Michaelis-Menten kinetics, what happens to the reaction rate v when the substrate concentration [S] is much greater than Km?
• In a rate law, what does k represent?
• Which expression represents a zero-order reaction with respect to the reactants A and B?
• In competitive inhibition, how are Km and Vmax affected?
• In a reversible first-order A ⇌ B with forward rate k1 and reverse rate k-1, how is the equilibrium constant defined in terms of rate constants?
• What is the steady-state approximation commonly used for?
• What is rate law?
• Which statement best describes chain branching in radical reactions?
• What describes the effect of an effective collision on reaction rate?
• How would you determine the activation energy Ea experimentally from rate data at different temperatures?
• Which statement is true about rate-determining steps?
• In heterogeneous catalysis, what effect does increasing surface area have on the rate?
• Which statement about reaction intermediates is true?
• Which thermodynamic quantities appear in the Eyring equation?
• Which statement best describes how reactant concentration affects collision theory?
• For a reaction with rate law rate = k [A]^2 [B], determine the overall order and how to experimentally determine the exponents
• Which plot would be linear for a zero-order reaction?
• If [A] doubles in a first-order reaction, what happens to the rate?
• For a second-order reaction with a single reactant A, which of the following is the correct integrated rate law and corresponding half-life?
• The natural logarithm is a logarithm with which base?
• In Arrhenius context, the pre-exponential factor A represents what physical concept?
• Under saturating substrate conditions, how does the rate depend on substrate concentration [S]?
• Termolecular steps are rare in elementary reactions because
• Which expression represents the integrated rate law for a second-order reaction?
• Which plot would be linear for a second-order reaction of A → products with rate = k[A]^2?
• In a multi-step reaction, which step determines the overall rate?
• Which expression is the integrated rate law for a zero-order reaction?
• Which statement is true about rate laws for non-elementary steps?
• To determine the reaction order with respect to a specific reactant, what procedure should you follow?
• What is the meaning of k units for a first-order reaction?
• In a chain-branching radical mechanism, what is the typical effect on the overall rate when a branching step yields two radicals from one radical?
• What is the initial-rate method for determining the rate law, and what data are typically collected?
• How does solvent viscosity affect diffusion-controlled reactions?
• In the Arrhenius equation, what is the general effect of increasing temperature on the rate constant k?
• What does rate law depend on?
• For a first-order reaction, which expression correctly gives the half-life t1/2 in terms of the rate constant k?
• In Michaelis-Menten kinetics, Km is a good indicator of substrate affinity under which condition?
• How does concentration affect rate?
• Vmax is given by Vmax = k2 [ET], where [ET] is the total enzyme concentration. Which option correctly states Vmax?
• In the description of the rate law, which statement is true about rate, rate constant, and concentrations?
• If the rate law is rate = k[A]^2, by what factor does the rate increase when [A] is doubled?
• If a plot of ln k versus 1/T is a straight line, what information can you extract and how?
• For a reversible reaction A ⇌ B with forward rate kf[A] and backward rate kb[B], which statement is true at equilibrium?
• What is the general effect of increasing temperature on a rate constant according to Arrhenius behavior?
• In the rate law, what does the exponent indicate?
• Which describes the induction time in a clock reaction?
• Which rate law expresses the rate as a function of reactant concentrations raised to powers?
• In a pseudo-first-order condition, what is the form of the integrated rate law?
• Which statement about a catalyst is true?
• In a fast pre-equilibrium Step 1: A ⇌ I and Step 2: I → P (slow), what is the resulting rate law in terms of [A] and [B]?
• Rate-limiting or rate-determining step
• In the context of enzyme kinetics, what does Vmax represent?
• Which statement describes the rate-determining step's position in the mechanism?
• How would you determine the rate constant k from a zero-order experiment?
• True or false: The rate law for a reaction must have exponents equal to the coefficients in the balanced equation.
• How does temperature affect rate?
• In chemical kinetics, the instantaneous rate at a given moment is defined as:
• Km is defined as the substrate concentration at half-maximum velocity.
• How is the rate of reaction defined with respect to product concentration?
• In the Eyring equation, which relationship connects ΔG‡, ΔH‡, and ΔS‡?
• What is the physical meaning of the pre-exponential factor A in the Arrhenius equation?
• For a second-order reaction, which plot yields a straight line?
• In a Lineweaver-Burk plot for competitive inhibition, what characteristic does the location of the intercepts have?
• Which expression correctly represents the rate law of an elementary step that involves three molecular entities A, B, and C?
• If a reaction mechanism contains a slow step and a fast step, which expression best describes the dependence of the rate on reactant concentrations for an elementary slow step A + B → products?
• For a mechanism in which Step 1: A + B → C is slow and Step 2: C → P is fast, what is the rate law?
• Besides the rate constant, what factors determine the rate in the rate law?
• In an Arrhenius plot of ln k versus 1/T, the slope represents...
• What is the Michaelis-Menten equation and the definitions of Vmax and Km?