Unit 11: Reaction Kinetics

21. Which of the following methods can be used to determine the order of a reaction experimentally?

a) Measuring the color change
b) Monitoring the pressure changes
c) Measuring the change in concentration over time
d) All of the above
Answer: d) All of the above

22. The half-life of a reaction is defined as:

a) The time required for the reactant concentration to decrease to half its initial value
b) The time required for the reaction to reach equilibrium
c) The time required for the product concentration to double
d) The time required for the reaction to complete
Answer: a) The time required for the reactant concentration to decrease to half its initial value

23. For a zero-order reaction, the rate of reaction is:

a) Independent of the concentration of reactants
b) Directly proportional to the concentration of reactants
c) Inversely proportional to the concentration of reactants
d) Proportional to the square of the concentration of reactants
Answer: a) Independent of the concentration of reactants

24. The Arrhenius equation relates the rate constant (k) to:

a) The concentration of reactants
b) The activation energy and temperature
c) The volume of the reaction mixture
d) The pressure of the reaction
Answer: b) The activation energy and temperature

25. How does a catalyst affect the activation energy of a reaction?

a) It increases the activation energy
b) It decreases the activation energy
c) It has no effect on the activation energy
d) It changes the reaction mechanism
Answer: b) It decreases the activation energy

26. What is the effect of adding a catalyst to a reaction?

a) It changes the equilibrium position
b) It increases the activation energy
c) It speeds up the rate of the reaction without being consumed
d) It decreases the concentration of reactants
Answer: c) It speeds up the rate of the reaction without being consumed

27. In which type of reaction does the rate decrease as the reaction progresses due to a decrease in the concentration of reactants?

a) Zero-order reaction
b) First-order reaction
c) Second-order reaction
d) Third-order reaction
Answer: b) First-order reaction

28. The method of initial rates involves:

a) Measuring the rate of reaction at different temperatures
b) Measuring the rate of reaction at different concentrations of reactants
c) Measuring the concentration of products at different times
d) Measuring the activation energy of the reaction
Answer: b) Measuring the rate of reaction at different concentrations of reactants

29. What does the term “reaction mechanism” refer to?

a) The overall rate of the reaction
b) The series of elementary steps that lead to the formation of products
c) The activation energy of the reaction
d) The effect of temperature on the reaction rate
Answer: b) The series of elementary steps that lead to the formation of products

30. A reaction mechanism that involves more than one elementary step is called:

a) A single-step reaction
b) A multi-step reaction
c) A zero-order reaction
d) A first-order reaction
Answer: b) A multi-step reaction