Question

The plot that represents the zero-order reaction is:

• A. \( \includegraphics[width=3cm]{92a.png} \)
• B. \( \includegraphics[width=3cm]{92b.png} \)
• C. \( \includegraphics[width=3cm]{92c.png} \)
• D. \( \includegraphics[width=3cm]{92d.png} \)

Hint:

For zero-order reactions, always focus on the linear relationship between concentration and time. The slope of the graph gives the negative value of the rate constant (\( -k \)).

Answer 1

The Correct Option is B

we start by analyzing the characteristics of a zero-order reaction. The defining feature of zero-order kinetics is that the rate of reaction does not depend on the concentration of the reactant. The rate law is given as: \[ r = k[\text{R}]^0 = k. \] This indicates a constant rate of reaction throughout the process. Graphical Approach: For a zero-order reaction, the integrated rate equation is: \[ [\text{R}] = [\text{R}_0] - k t, \] where \( [\text{R}_0] \) is the initial concentration, \( k \) is the rate constant, and \( t \) is time. This equation represents a straight-line graph when \( [\text{R}] \) is plotted against \( t \), with: - Slope = \( -k \) (negative value due to the decreasing concentration over time). - Y-intercept = \( [\text{R}_0] \). Deriving the Correct Plot: To verify the graphical representation, consider the following steps: 1. At \( t = 0 \): \( [\text{R}] = [\text{R}_0] \), which matches the y-intercept. 2. At \( t = \frac{[\text{R}_0]}{k} \): \( [\text{R}] = 0 \), which corresponds to the time at which the reactant is fully consumed. Thus, the plot of \( [\text{R}] \) versus \( t \) will be a straight line with a downward slope, consistent with the equation. Final Answer: (2) \( \includegraphics[width=3cm]{92b.png} \)