Chemical Engineering - Chemical Reaction Engineering - Discussion
Discussion Forum : Chemical Reaction Engineering - Section 2 (Q.No. 17)
17.
If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the __________ diffusion.
Discussion:
1 comments Page 1 of 1.
Taisir said:
3 months ago
The correct answer is (Ash diffusion) :
Explanation:
In a solid-gas non-catalytic reaction (e.g., combustion of a solid particle or gas-solid reactions), several steps are involved:
Diffusion of gaseous reactant through the gas film surrounding the solid particle.
Diffusion through the ash layer formed on the surface of the solid.
Chemical reaction at the unreacted solid surface.
At very high temperatures, the chemical reaction rate is high-speed, so it is not the limiting factor.
Also, gas film diffusion becomes less significant at high temperatures due to increased diffusivity and turbulence.
However, the diffusion of reactant through the ash layer becomes the rate-controlling step, especially as the reaction progresses and the ash layer thickens.
Explanation:
In a solid-gas non-catalytic reaction (e.g., combustion of a solid particle or gas-solid reactions), several steps are involved:
Diffusion of gaseous reactant through the gas film surrounding the solid particle.
Diffusion through the ash layer formed on the surface of the solid.
Chemical reaction at the unreacted solid surface.
At very high temperatures, the chemical reaction rate is high-speed, so it is not the limiting factor.
Also, gas film diffusion becomes less significant at high temperatures due to increased diffusivity and turbulence.
However, the diffusion of reactant through the ash layer becomes the rate-controlling step, especially as the reaction progresses and the ash layer thickens.
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