Which of the following graphs most appropriately represents a zero-order reaction?
A
(1)
B
(2)
C
(3)
D
(4)

Question

Which of the following graphs most appropriately represents a zero-order reaction?

Accepted Answer

Given: A graph-based question on a zero-order reaction.

Find: Which graph correctly represents the behavior of a zero-order reaction.

For a zero-order reaction, the rate is constant and does not depend on reactant concentration:

\text{Rate} = k

The integrated rate law is:

[A] = [A]_0 - kt

This is the equation of a straight line:

y = mx + c

So, a plot of reactant concentration $[A]$ versus time $t$ must be a straight line with negative slope $-k$ and intercept $[A]_0$ .

Therefore, the correct graph is the one showing reactant concentration decreasing linearly with time, which is option (2).

The correct option is B.

Other graphs are incorrect because a horizontal concentration-time graph would imply no reaction progress, a curved concentration-time graph corresponds to a different order, and a decreasing rate-time straight line does not represent zero-order behavior since the rate remains constant in zero-order kinetics.

Given: Zero-order kinetics.

Find: The appropriate graph.

In zero-order kinetics, the rate law is:

\text{Rate} = k

Hence the rate remains constant throughout the reaction.

Using the integrated form:

[A] = [A]_0 - kt

we see that reactant concentration decreases by equal amounts in equal intervals of time. Therefore, the graph of $[A]$ against $t$ is linear with a negative slope.

So the graph marked (2) matches zero-order behavior, and hence the correct option is B.

Answer

Step-by-step solution

Common mistakes

Practice more Order & Molecularity questions

Related questions