Question

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

• A.
• B.
• C.
• D.

Hint:

For zero-order reactions, the concentration decreases linearly with time, and the rate is constant over the course of the reaction.

Answer 1

The Correct Option is B

To address this problem, understanding zero-order chemical reaction characteristics is essential. In such reactions, the rate is constant and unaffected by reactant concentrations.

The rate equation for a zero-order reaction is:

\[\text{Rate} = k\]

where \(k\) denotes the rate constant.

The integrated rate law for a zero-order reaction is:

\[[A] = [A]_0 - kt\]

Here, \([A]\) is the reactant concentration at time \(t\), \([A]_0\) is the initial concentration, \(k\) is the rate constant, and \(t\) is the elapsed time.

This equation aligns with the linear equation form:

\[y = mx + c\]

In this context, \([A]\) corresponds to \(y\), time \(t\) to \(x\), \(-k\) to the slope \(m\), and \([A]_0\) to the intercept \(c\).

Consequently, a plot of \([A]\) versus \(t\) for a zero-order reaction will yield a straight line with a negative slope. Among the given options, the correct graph representing a zero-order reaction is:

This graph clearly illustrates a linear decline in concentration over time, characteristic of a zero-order reaction.

Explanation of why other options are incorrect:

• Graphs representing other reaction orders (e.g., first or second order) would typically show a nonlinear relationship between concentration and time.