Spontaniety of gas(Nitrogen) adsorption over solid(Zeolite).

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In summary, the speaker was researching adsorption and wanted to know how spontaneous the process is. They performed calculations using the equation dG = dH - T*dS and found that nitrogen adsorption over zeolite was a non-spontaneous process. They also speculated that adsorption requires pressure, which may contribute to the negative dG. They are seeking further understanding and opinions on the topic.
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AbhiNature
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Hello!

The other day I was reading about adsorption(gas over solid), and there it stated that it is a spontaneous process. I wanted to know how spontaneous the process is. I therefore took nitrogen adsorption over zeolite as a candidate to find its spontaneity, and to my surprise, my calculations showed it to be a non-spontaneous process. I guess I am wrong somewhere, but I just cannot find where.

Following are the calculations that I did;
dG = dH - T*dS
Assuming adsorption to be equivalent to converting gas to liquid.
Therefore,
dH = Heat of vaporization of Nitrogen = -5560J/mole
T = 300K (Adsorption at 300K).
S1 = Entropy of Nitrogen at 300K = 192J/moleK.
S2 = Entropy of Nitrogen in liquid form (I did not find entropy data of liquid Nitrogen, but I did find data at 100K) = 160J/moleK.

Which gives,
dG = 4040J/mole - non-spontaneous.

I saw a graph which showed quite a lot of adsorption at 300K.

I speculate that, adsorption needs pressure and the source of this pressure has more than enough negative dG?

Could you please help me understand this?

Thanks!
 
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No reply? Not even an opinion?
 

Related to Spontaniety of gas(Nitrogen) adsorption over solid(Zeolite).

1. What is the mechanism of gas adsorption over solid zeolite?

The mechanism of gas adsorption over solid zeolite is based on the Van der Waals forces between the gas molecules and the surface of the zeolite. As the gas molecules come into contact with the zeolite surface, they are attracted to the negatively charged sites on the zeolite, leading to adsorption.

2. Why is nitrogen commonly used for gas adsorption experiments?

Nitrogen is commonly used for gas adsorption experiments because it is readily available, non-toxic, and inert. It also has a relatively small molecular size, making it ideal for studying the pore structures of solid materials.

3. How does the temperature affect the spontaneity of gas adsorption over solid zeolite?

The temperature can greatly affect the spontaneity of gas adsorption over solid zeolite. At lower temperatures, the adsorption process is more spontaneous, as the gas molecules have less energy and are more likely to be attracted to the zeolite surface. However, at higher temperatures, the adsorption process becomes less spontaneous as the gas molecules have more thermal energy and are less likely to be attracted to the zeolite surface.

4. Can the pore size and structure of zeolite affect the spontaneity of gas adsorption?

Yes, the pore size and structure of zeolite can greatly affect the spontaneity of gas adsorption. The size of the zeolite pores must be large enough to allow gas molecules to enter and be adsorbed, but small enough to prevent larger molecules from entering. Additionally, the structure of the zeolite can affect the strength of the Van der Waals forces between the gas molecules and the zeolite surface, influencing the spontaneity of the adsorption process.

5. How is the spontaneity of gas adsorption over solid zeolite measured?

The spontaneity of gas adsorption over solid zeolite is typically measured by calculating the change in Gibbs free energy (∆G) during the adsorption process. A more negative ∆G value indicates a more spontaneous adsorption process, while a positive value indicates a non-spontaneous process.

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