Chemistry - Chemical Kinetics - MCQs
Learn about the speed of chemical reactions, reaction mechanisms, and factors affecting reaction rates.
For a reaction with the rate law Rate = k[A][B]², how is the rate affected if the concentration of B is tripled?
A. The rate stays the same
B. The rate triples
C. The rate increases ninefold
D. The rate halves
Answer: The rate increases ninefold
How does a higher activation energy affect the rate of a reaction?
A. It increases the reaction rate
B. It decreases the reaction rate
C. It has no effect on the rate
D. It doubles the rate of reaction
Answer: It decreases the reaction rate
Which statement best describes the transition state of a chemical reaction?
A. It is the state where reactants are converted to products
B. It is a low-energy state of the system
C. It is the point where the system has the highest energy
D. It is the final state of the reaction
Answer: It is the point where the system has the highest energy
What effect does increasing the surface area of a solid reactant have on the rate of reaction?
A. It decreases the rate of reaction
B. It has no effect
C. It increases the rate of reaction
D. It slows down the reaction
Answer: It increases the rate of reaction
What is the overall order of a reaction with the rate law Rate = k[A]²[B]?
A. Zero
B. First
C. Second
D. Third
Answer: Third
In a second-order reaction, if the concentration of the reactant is doubled, how is the rate affected?
A. The rate remains the same
B. The rate doubles
C. The rate quadruples
D. The rate halves
Answer: The rate quadruples
Which reaction is most likely to have a rate law that includes the term [A][B]?
A. A reaction with two products
B. A reaction with two reactants
C. A reaction that is zero-order
D. A reaction that is first-order
Answer: A reaction with two reactants
Which of the following plots will yield a straight line for a first-order reaction?
A. Concentration vs. time
B. ln(Concentration) vs. time
C. 1/Concentration vs. time
D. Rate vs. concentration
Answer: ln(Concentration) vs. time
How does the presence of a catalyst affect the energy profile of a reaction?
A. It increases the energy of the reactants
B. It decreases the energy of the products
C. It lowers the activation energy
D. It increases the enthalpy change of the reaction
Answer: It lowers the activation energy
Which of the following statements is true about the half-life of a first-order reaction?
A. It depends on the initial concentration of the reactant
B. It is directly proportional to the concentration of the reactant
C. It remains constant throughout the reaction
D. It decreases as the reaction progresses
Answer: It remains constant throughout the reaction