Question

Thiele modulus is not a function of initial concentration for which of the following order reactions

• A. 4th
• B. 3rd
• C. 2nd
• D. 1st

Hint:

For higher-order reactions (such as 4th or 5th), the dependence of Thiele modulus on initial concentration is diminished.

Answer 1

The Correct Option is A

Step 1: Understanding Thiele modulus.
The Thiele modulus (\( \phi \)) is used to describe the effectiveness of the catalyst in porous media and is a function of the rate of reaction and the diffusion rate. For most reactions, the Thiele modulus depends on the initial concentration. However, for higher-order reactions, particularly 4th order and beyond, the dependence of Thiele modulus on initial concentration becomes less significant. This is because at higher orders, the reaction rate is more influenced by the geometry and mass transfer properties rather than by the initial concentration.
Step 2: Conclusion.
The correct answer is (1), the 4th-order reaction, where the Thiele modulus is not a function of the initial concentration.