Question

Arrange the steps involved in the gas transfer from gas bubble into bulk liquid
[A.] The gaseous component diffused through the quiescent liquid film into the bulk liquid. 
[B.] The gaseous component enters into the liquid film. 
[C.] Transportation of the gaseous component into the well mixed bulk liquid. 
[D.] The aeseous component transported from the bulk gas to gas-liquid interphase. 
Choose the most appropriate answer from the options given below:

• A. D, B, A, C
• B. D, C, B, A
• C. C, D, B, A
• D. D, B, C, A

Hint:

The path for mass transfer across an interface is always: Bulk of Phase 1 \(\rightarrow\) Film in Phase 1 \(\rightarrow\) Interface \(\rightarrow\) Film in Phase 2 \(\rightarrow\) Bulk of Phase 2. The question combines some of these steps, but the overall sequence remains the same.

Answer 1

The Correct Option is A

Step 1: Apply the two-film theory of mass transfer to visualize the process. This theory posits a stagnant gas film and a stagnant liquid film at the gas-liquid interface.

Step 2: Trace the path of a gas molecule from the bubble to the liquid.
1. (D) The molecule must first travel from the interior (bulk) of the gas bubble to the surface of the bubble (the gas-liquid interface).
2. (B) The molecule then crosses the interface and enters the stagnant liquid film that surrounds the bubble.
3. (A) The molecule must then travel across this stagnant liquid film via molecular diffusion.
4. (C) Once it exits the film, it is transported into the main body (bulk) of the liquid, which is assumed to be well-mixed, usually by convection.
The correct logical sequence is D \(\rightarrow\) B \(\rightarrow\) A \(\rightarrow\) C.