Which of the following adsorption isotherms represents the adsorption of a gas by a solid involv

Which of the following adsorption isotherms represents the...

Key Concepts

BET (Brunauer, Emmett, Teller) Theory

The BET theory extends the Langmuir model of adsorption to account for the formation of multiple layers of adsorbate on a surface. It provides a mathematical framework to describe multilayer adsorption, allowing for the determination of surface area and pore size distribution. The BET isotherm is widely used in both research and industry to analyze the characteristics of porous materials and to predict their adsorption behavior under different conditions.

Adsorption Isotherm

An adsorption isotherm describes the relationship between the pressure (or concentration) of a gas and the amount of gas adsorbed on a solid surface at constant temperature. It is a fundamental concept in surface chemistry used to characterize the interaction between adsorbate molecules and an adsorbent, thereby providing insights into surface properties such as surface area and porosity.

Multilayer Adsorption

Multilayer adsorption refers to the phenomenon where, beyond the initial adsorption of a single monolayer of molecules on a surface, additional layers begin to form. This process occurs as the gas pressure increases, and it is important in understanding and modeling how molecules interact with surfaces beyond just the first layer. It distinguishes systems where adsorption is not limited to a monolayer, influencing properties like adsorption capacity and energy distribution.

Transcript

00:01 Okay, so the question is which one of these graphs represents multi -resolution of a gas on solid surface.

00:09 Actually, the question itself, it's a bit vague since it doesn't indicate if the solid surface is porous, if it's not porous, or what's the affinity of the gas to the surface, it's high affinity, low affinity, so that to actually pick, one of these accurately, one of these graphs.

00:34 I just give some explanation here, though i do not want to refer to the right answer directly.

00:41 I just want you, the student, just to understand the meaning of absorption or this absorption of a gas on solid surface so that you can pick or you can decide yourself which one you want to pick among the answers.

00:58 So with the first graph here, we would see that saturation pressure here, the graph shows there is a saturation pressure that the absorption reaches to.

01:13 So that means the absorption doesn't continue beyond that layer of saturation.

01:20 This is typical of a monolayer absorption.

01:24 So we wouldn't normally consider this as multi -layer absorption.

01:29 So once there is a saturation reached, there is no more, no further absorption.

01:34 Similar is true with b, since this one also, actually it could be like a double layer or very limited number, okay, of layers.

01:49 As you see, there is a second layer, but there is still a saturation reached.

01:53 Okay.

01:54 So as you see here again, there is a saturation.

01:57 There is no further absorption...

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