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10:06 PM
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A: What is the meaning of a "free energy per unit surface area" vs "pressure" plot?

Nike DattaniThe graph does show that at high pressures the $\Delta G$ per surface area values are lower, which would usually indicate stability. I agree with you that as the pressure goes lower, the stability reduces. However I disagree regarding temperature: As the temperatures decrease (from the green curv...

Ok thanks Sir for the explanation. Does it mean when the free energy becomes positive as seen at low pressures and high temperatures (1100 - 1500 K) there will be desorption? — Nana Kofi Boakye yesterday
If what is plotted is $\Delta G = G_{\textrm{adsorbed} - G_{\textrm{desorbed}$, then a positive value would mean that the desorbed of the system has a lower free energy and is hence more stable. This would suggest to me that desoption would occur at low pressures and from 1100K to 1500K. From where did you get this figure? — Nike Dattani yesterday
Please try to use full sentences when you communicate to me. — Nike Dattani yesterday
Sorry for that I was only showing the link to the earlier post since I can't type the equation in a comment. So I have an oxidized surface. And I want to check the stability of the surface with variation in pressure and temperature as the link depicts. — Nana Kofi Boakye yesterday
Equations can be typed in comments the same way that they can be done for posts, but the equation in my comment from 50 minutes ago does not appear correctly because I forgot two closing brackets! Here is the equation: $\Delta G = G_{\textrm{adsorbed}} - G_{\textrm{desorbed}}$. — Nike Dattani yesterday
$G_{ads} = E_{oxidized} + F_{vib} - E_{clean} - N_O\left [\frac{1}{2}E_{O_2} + \Delta\mu_O(T,P^0) + \frac{2.303}{2}k_BTlog\left(\frac{P_{O_2}}{P_O}\right ) \right ]$. This is the equation I plotted. From literature, the authors talk about desorption at positive $G_{ads}$ — Nana Kofi Boakye yesterday
 

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