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 overview.
The Lindemann mechanism suggests that the decomposition of a molecule follows first-order kinetics at low pressure, where the rate of decomposition is dependent on the concentration of the reactant. At high pressures, the reaction can follow second-order kinetics due to the increased number of collisions.

Step 2: Analysis of options.
- (1) It follows second order kinetics at high pressure: This is true for high-pressure conditions, but not the best fit for the unimolecular decomposition at low pressure.
- (2) It follows second order kinetics at low pressure: This is not correct; Lindemann mechanism typically follows first-order kinetics at low pressure.
- (3) The kinetics of the reaction does not depend on the gaseous pressure: This is not accurate; the kinetics depend on pressure.
- (4) It follows first order kinetics at low pressure: This is correct according to the Lindemann mechanism.

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