Chem 2 Chapter 14 Questions Part 1 PDF

**Reaction Rates and Rate Laws** 1. What is the most common unit used to express reaction rate?\ A) Moles per liter per second (M/s)\ B) Grams per second (g/s)\ C) Atoms per second\ D) Moles per liter per minute (M/min)\ E) Atmospheres per second (atm/s)\ **Answer:** A) Mol...

**Reaction Rates and Rate Laws** 1. What is the most common unit used to express reaction rate?\ A) Moles per liter per second (M/s)\ B) Grams per second (g/s)\ C) Atoms per second\ D) Moles per liter per minute (M/min)\ E) Atmospheres per second (atm/s)\ **Answer:** A) Moles per liter per second (M/s) 2. Which of the following statements about reaction rate is true?\ A) Reaction rate can be negative.\ B) The rate of a reaction depends only on temperature.\ C) The rate of disappearance of reactants is always reported as negative.\ D) Reaction rates must always be determined experimentally.\ E) The rate law is determined from the balanced equation.\ **Answer:** D) Reaction rates must always be determined experimentally. 3. In the reaction A + B → 2C, how does the rate of disappearance of A compare to the rate of formation of C?\ A) The same\ B) Twice as fast\ C) Half as fast\ D) Four times as fast\ E) No relationship\ **Answer:** C) Half as fast 4. What does the rate law describe?\ A) The stoichiometry of the reaction\ B) How the rate depends on reactant concentrations\ C) The equilibrium position of the reaction\ D) The total amount of product formed\ E) The amount of energy released in the reaction\ **Answer:** B) How the rate depends on reactant concentrations 5. What does the rate constant (k) depend on?\ A) The concentration of the reactants\ B) The order of the reaction\ C) The temperature of the reaction\ D) The pressure of the system\ E) The catalyst concentration\ **Answer:** C) The temperature of the reaction **Reaction Order and Integrated Rate Laws** 6. If a reaction is zero order in reactant A, how does the rate change when A is doubled?\ A) The rate doubles.\ B) The rate is halved.\ C) The rate remains constant.\ D) The rate quadruples.\ E) The rate decreases.\ **Answer:** C) The rate remains constant. 7. A reaction is first order in \[A\]. What happens to the rate when \[A\] is tripled?\ A) The rate doubles.\ B) The rate triples.\ C) The rate is squared.\ D) The rate is halved.\ E) The rate remains unchanged.\ **Answer:** B) The rate triples. 8. A second-order reaction is one where:\ A) The concentration of one reactant is squared in the rate law.\ B) The reaction involves two reactants.\ C) The rate constant has units of M/s.\ D) The reaction occurs in two steps.\ E) The concentration of the reactant has no effect on rate.\ **Answer:** A) The concentration of one reactant is squared in the rate law. 9. The half-life equation **t₁/₂ = 0.693/k** applies only to:\ A) Zero-order reactions\ B) First-order reactions\ C) Second-order reactions\ D) Reversible reactions\ E) Third-order reactions\ **Answer:** B) First-order reactions 10. Which of the following is NOT a valid unit for the rate constant (k)?\ A) 1/s\ B) 1/(M²·s)\ C) M²/s\ D) M/s\ E) 1/(M·s)\ **Answer:** C) M²/s **Collision Theory and Activation Energy** 11. According to collision theory, which condition is NOT necessary for a reaction to occur?\ A) Proper molecular orientation\ B) Sufficient energy\ C) Correct temperature\ D) A catalyst\ E) Frequent collisions\ **Answer:** D) A catalyst 12. Increasing the temperature of a reaction generally:\ A) Decreases the activation energy\ B) Increases the rate constant (k)\ C) Lowers the frequency of collisions\ D) Decreases the number of successful collisions\ E) Does not affect reaction rate\ **Answer:** B) Increases the rate constant (k) 13. A catalyst affects a reaction by:\ A) Lowering the activation energy\ B) Increasing the activation energy\ C) Changing the reactants\ D) Altering the equilibrium constant\ E) Consuming reactants faster\ **Answer:** A) Lowering the activation energy 14. The rate-determining step is:\ A) The fastest step in a reaction mechanism\ B) The step with the highest activation energy\ C) The step with the lowest activation energy\ D) Always the last step\ E) The step that involves a catalyst\ **Answer:** B) The step with the highest activation energy 15. What is the molecularity of the reaction step: A + B → C?\ A) Unimolecular\ B) Bimolecular\ C) Trimolecular\ D) Zero order\ E) None of the above\ **Answer:** B) Bimolecular **Reaction Mechanisms and Rate-Determining Steps** 16. In the two-step mechanism below, which step determines the rate law?\ Step 1: A + B → C (slow)\ Step 2: C + D → E (fast)\ A) Step 1\ B) Step 2\ C) Both steps\ D) Neither step\ E) It depends on the reactants\ **Answer:** A) Step 1 17. Which of the following is an example of a reaction intermediate?\ A) A catalyst\ B) A product\ C) A reactant\ D) A species formed in one step and consumed in another\ E) A spectator ion\ **Answer:** D) A species formed in one step and consumed in another 18. The slowest step in a reaction mechanism:\ A) Is always the first step\ B) Limits the overall rate of reaction\ C) Does not affect the rate law\ D) Occurs after the fast steps\ E) Always involves a catalyst\ **Answer:** B) Limits the overall rate of reaction 19. Which of the following describes a catalyst?\ A) Appears in the overall reaction equation\ B) Lowers the reaction's activation energy\ C) Is consumed in the reaction\ D) Increases the reaction equilibrium constant\ E) Changes the reaction order\ **Answer:** B) Lowers the reaction's activation energy 20. Which step in a mechanism will determine the rate law?\ A) The fastest step\ B) The slowest step\ C) The step with the most reactants\ D) The step that releases the most energy\ E) The last step\ **Answer:** B) The slowest step **Temperature Effects, Catalysts, and Reaction Kinetics** 21. If the temperature of a reaction increases, the reaction rate generally:\ A) Decreases due to increased molecular motion\ B) Increases because molecules collide more frequently and with more energy\ C) Remains constant because the rate law does not change\ D) Decreases due to a decrease in activation energy\ E) Does not change unless a catalyst is present\ **Answer:** B) Increases because molecules collide more frequently and with more energy 22. A catalyst:\ A) Increases the energy of reactants\ B) Alters the equilibrium constant\ C) Increases the activation energy of the reaction\ D) Provides an alternative reaction pathway with lower activation energy\ E) Becomes a product in the reaction\ **Answer:** D) Provides an alternative reaction pathway with lower activation energy 23. Which of the following statements is true about reaction intermediates?\ A) They are included in the overall reaction equation\ B) They appear in the rate law\ C) They are consumed in a later step of the reaction mechanism\ D) They increase the reaction rate\ E) They are catalysts\ **Answer:** C) They are consumed in a later step of the reaction mechanism 24. For a reaction following a second-order rate law, which unit is correct for the rate constant (k)?\ A) s⁻¹\ B) M/s\ C) 1/(M·s)\ D) M²/s\ E) No units\ **Answer:** C) 1/(M·s) 25. What happens to the reaction rate if the reactant concentration is halved in a first-order reaction?\ A) It remains the same\ B) It doubles\ C) It halves\ D) It quadruples\ E) It increases by a factor of 3\ **Answer:** C) It halves **Half-Life and Integrated Rate Laws** 26. The half-life of a first-order reaction:\ A) Increases as concentration decreases\ B) Decreases as concentration decreases\ C) Is constant regardless of concentration\ D) Depends on the initial amount of reactant\ E) Is shorter for larger reactant concentrations\ **Answer:** C) Is constant regardless of concentration 27. The integrated rate law for a first-order reaction is:\ A) \[A\]t=\[A\]0−kt\[A\]\_t = \[A\]\_0 - kt\[A\]t​=\[A\]0​−kt\ B) ln⁡\[A\]t=ln⁡\[A\]0−kt\\ln\[A\]\_t = \\ln\[A\]\_0 - ktln\[A\]t​=ln\[A\]0​−kt\ C) 1/\[A\]t=1/\[A\]0+kt1/\[A\]\_t = 1/\[A\]\_0 + kt1/\[A\]t​=1/\[A\]0​+kt\ D) ln⁡\[A\]t=−kt\\ln\[A\]\_t = -ktln\[A\]t​=−kt\ E) \[A\]t=\[A\]0e−kt\[A\]\_t = \[A\]\_0 e\^{-kt}\[A\]t​=\[A\]0​e−kt\ **Answer:** B) ln⁡\[A\]t=ln⁡\[A\]0−kt\\ln\[A\]\_t = \\ln\[A\]\_0 - ktln\[A\]t​=ln\[A\]0​−kt 28. The half-life equation **t₁/₂ = 0.693/k** is derived from:\ A) The second-order rate law\ B) The Arrhenius equation\ C) The first-order integrated rate law\ D) The equilibrium expression\ E) The definition of reaction order\ **Answer:** C) The first-order integrated rate law 29. If a reaction has a rate law of **rate = k\[A\]²\[B\]**, what is the overall order of the reaction?\ A) 1\ B) 2\ C) 3\ D) 4\ E) 5\ **Answer:** C) 3 30. Which of the following factors does NOT affect the rate constant (k) of a reaction?\ A) Temperature\ B) Presence of a catalyst\ C) Activation energy\ D) Reactant concentration\ E) The nature of the reactants\ **Answer:** D) Reactant concentration