Question

Which of the following statement is true for Lindemann mechanism for the unimolecular decomposition of a molecule?

• A. It follows second order kinetics at high pressure.
• B. It follows second order kinetics at low pressure.
• C. The kinetics of the reaction does not depend on the gaseous pressure.
• D. It follows first order kinetics at low pressure.

Hint:

In the Lindemann mechanism, the reaction follows first-order kinetics at low pressures and second-order at high pressures.

Answer 1

The Correct Option is D

Step 1: Lindemann mechanism summary.
The Lindemann mechanism posits that molecule decomposition exhibits first-order kinetics at low pressure, with decomposition rate contingent on reactant concentration. At elevated pressures, collisions become more frequent, potentially leading to second-order kinetics.

Step 2: Option evaluation.
- (1) Second-order kinetics at high pressure: Accurate for high-pressure scenarios but not the primary low-pressure unimolecular decomposition characteristic.
- (2) Second-order kinetics at low pressure: Incorrect; the Lindemann mechanism typically shows first-order kinetics at low pressure.
- (3) Kinetics independent of gaseous pressure: Inaccurate; pressure influences the reaction kinetics.
- (4) First-order kinetics at low pressure: Correct, aligning with the Lindemann mechanism.

Step 3: Determination.
Option (4) is correct, as the reaction follows first-order kinetics at low pressure.