Question 1
Which of the following best describes the difference between instantaneous and average rates?
A. Instantaneous rate is the rate at a specific time, while average rate is over an interval.
B. Instantaneous rate is the rate over an interval, while the average rate is at a specific time.
C. Both instantaneous and average rates are calculated over specific intervals.
D. Both instantaneous and average rates are calculated at specific times.
Question 2
What are the units of the rate constant (k) for a second-order reaction?
A. s^(-1)
B. M^(-1) s^(-1)
C. M s^(-1)
D. No units
Question 3
Which method involves plotting concentration against time to determine the order of a reaction?
A. Graphical method
B. Initial rates method
C. Half-life method
D. Steady-state approximation
Question 4
What is the molecularity of an elementary step that involves a collision between two molecules?
A. Zero
B. First
C. Second
D. Third
Question 5
For a zero-order reaction, how does the rate of reaction change with an increase in the concentration of the reactant?
A. Increases
B. Decreases
C. Remains constant
D. Becomes unpredictable
Question 6
a) Define the term 'instantaneous rate' in the context of chemical kinetics. [2]
b) How does the instantaneous rate differ from the average rate of a reaction? [2]
Question 7
a) Describe the general form of a rate law and its components. [2]
b) Explain the significance of the rate constant (K) in the rate law. [2]
Question 8
a) What is meant by the term 'molecularity' in the context of reaction mechanisms? [2]
b) How does molecularity relate to the elementary steps of a reaction mechanism? [2]
Question 9
a) Explain the characteristics of a zero-order reaction. [2]
b) How can the reaction order be determined using graphical methods? [3]
c) Given a straight-line graph with time on the x-axis and concentration of reactant on the y-axis for a zero-order reaction, what does the slope of the line represent? [2]
Question 10
a) Describe the importance of elementary steps in understanding reaction mechanisms. [3]
b) If a reaction mechanism consists of two elementary steps, how can one determine the overall rate law? [3]
c) Define the steady-state approximation and its role in complex reactions. [2]