Question

For zero order reaction, when [A] is plotted against time (t), the slope of the straight line obtained is equal to

• A. –k
• B. k
• C. [A]$_0$
• D. –kt

Hint:

For zero-order reactions, the slope of the plot of concentration vs time is equal to the negative of the rate constant, -k.

Answer 1

The Correct Option is A

Step 1: Zero order reaction rate law.
For a zero-order reaction, the rate law is given by: \[ \text{Rate} = k \] The integrated rate law for a zero-order reaction is: \[ [A] = [A]_0 - kt \] Plotting [A] versus time gives a straight line with slope \( -k \).
Step 2: Analyzing the options.
(A) –k: This is the correct slope for the plot of [A] vs time for a zero-order reaction.
(B) k: This is incorrect, as the slope is negative in the zero-order reaction.
(C) [A]$_0$: This is incorrect, as it does not represent the slope of the plot.
(D) –kt: This is incorrect as well, as the slope is simply –k, not –kt.
Step 3: Conclusion.
The correct answer is (A) –k.