Questions on Reaction Rate
Multiple-Choice Questions: Reaction Rate
1. What is the definition of the rate of a chemical reaction?
A) The amount of product at equilibrium
B) The time it takes for a reaction to complete
C) The change in concentration of a reactant or product per unit time
D) The speed at which energy is released
E) The total energy change during the reaction
2. Which factor does not directly affect the rate of a chemical reaction?
A) Temperature
B) Catalyst presence
C) Pressure (for gases)
D) Molecular weight of the products
E) Concentration of reactants
3. How does increasing the temperature generally affect the rate of a chemical reaction?
A) It decreases the activation energy
B) It increases the reaction rate
C) It stops the reaction
D) It decreases the number of collisions
E) It changes the stoichiometry
4. Which statement about catalysts is correct?
A) Catalysts increase the activation energy
B) Catalysts are consumed during the reaction
C) Catalysts shift the equilibrium position
D) Catalysts increase the rate by providing an alternative pathway
E) Catalysts reduce the product yield
5. What does the collision theory state?
A) All molecules in a reaction collide with equal energy
B) Reactions occur only when particles collide with sufficient energy and proper orientation
C) Energy is always released in a collision
D) Reactions occur only in aqueous solutions
E) Collisions always result in product formation
6. Which unit is commonly used for the rate of a reaction involving gases?
A) mol/g
B) g/L·s
C) atm/s
D) mol/L·s
E) L/mol·s
7. What effect does a higher concentration of reactants usually have on the reaction rate?
A) No effect
B) Slows down the reaction
C) Increases the number of effective collisions
D) Increases the activation energy
E) Lowers the temperature
8. The rate law for a reaction is given by: Rate = k[A][B]^2. What is the overall order of the reaction?
A) 1
B) 2
C) 3
D) 4
E) Cannot be determined
9. In the rate law Rate = k[A]^2, what happens to the rate if [A] is doubled?
A) The rate remains the same
B) The rate doubles
C) The rate quadruples
D) The rate triples
E) The rate is halved
10. What is the role of the rate constant (k) in a rate law?
A) It measures the equilibrium position
B) It gives the energy change of the reaction
C) It depends only on the catalyst
D) It determines the speed of the reaction at a given temperature
E) It remains constant regardless of conditions
11. Which graph typically shows a straight line for a first-order reaction?
A) [A] vs time
B) ln[A] vs time
C) 1/[A] vs time
D) Rate vs time
E) Rate vs [A]
12. Which change would most effectively increase the rate of a reaction between two gases?
A) Decreasing the pressure
B) Lowering the temperature
C) Adding an inert gas
D) Increasing the pressure
E) Reducing the volume of the container
13. What is the activation energy of a reaction?
A) The energy required to break product bonds
B) The energy released during a reaction
C) The energy required to initiate the reaction
D) The energy of the reactants
E) The total energy change in the reaction
14. Which factor affects the value of the rate constant (k)?
A) Pressure only
B) Volume of the reaction container
C) Temperature
D) Concentration of reactants
E) Time elapsed in the reaction
15. What does the Arrhenius equation relate?
A) Rate and product yield
B) Concentration and time
C) Rate constant and temperature
D) Pressure and rate
E) Rate and molecular weight
16. What is the function of a catalyst in a reaction mechanism?
A) Increases activation energy
B) Increases product stability
C) Alters the stoichiometric coefficients
D) Increases the rate-determining step speed
E) Eliminates intermediates
17. A reaction is zero-order in A. What happens to the rate if [A] is tripled?
A) Rate triples
B) Rate remains unchanged
C) Rate doubles
D) Rate becomes zero
E) Rate decreases
18. The rate-determining step in a reaction mechanism is:
A) The fastest step
B) The last step in the mechanism
C) The step involving the highest energy transition state
D) The step producing the most intermediates
E) The step with the smallest molecularity
19. What happens to the reaction rate if a catalyst is removed from the reaction mixture?
A) It increases
B) It remains unchanged
C) It initially increases, then decreases
D) It decreases
E) It becomes infinite
20. Which of the following is true about reaction mechanisms?
A) They are always single-step reactions
B) The slowest step determines the overall rate
C) All steps occur at the same rate
D) The first step is always the rate-determining step
E) Intermediates are always present in the overall equation
- Questions about the Heat of Solution
- Questions about Hess's Law of Heat Summation
- Questions about Heat of Combustion
Answer Key with Explanations
1. C – Rate is the change in concentration over time.
2. D – Molecular weight of products does not directly affect rate.
3. B – Higher temperature increases molecular motion and collisions.
4. D – Catalysts provide an alternative path with lower activation energy.
5. B – Collision theory emphasizes energy and orientation.
6. D – mol/L·s is standard for rate in solution or gas phase.
7. C – Higher concentration means more frequent collisions.
8. C – Overall order = sum of exponents = 1 + 2 = 3.
9. C – Doubling [A] in Rate = k[A]^2 quadruples the rate.
10. D – The rate constant reflects how fast a reaction proceeds.
11. B – ln[A] vs time is linear for first-order reactions.
12. D – Higher pressure increases concentration of gas molecules.
13. C – Activation energy is needed to start the reaction.
14. C – Temperature affects the kinetic energy and thus the rate constant.
15. C – The Arrhenius equation links rate constant to temperature.
16. D – A catalyst speeds up the rate-determining step.
17. B – In zero-order, rate is independent of concentration.
18. C – The step with highest energy barrier controls the rate.
19. D – Without catalyst, reaction proceeds slower.
20. B – The slowest step controls the overall rate.
Dive into the groundbreaking science of neurotransmitters—your brain’s invisible architects—in Chemical Harmony: How Neurotransmitters Shape Our Lives (2025). This meticulously researched book reveals how serotonin, dopamine, GABA, and other brain chemicals silently orchestrate every aspect of your existence, from decision-making and relationships to mental health and emotional resilience.Click here to buy
Share Online!
