Questions tagged [surface-chemistry]
Surface chemistry is roughly defined as the study of chemical reactions at interfaces between 2 or more phases.
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What is the limitation of Freundlich Isotherm? [on hold]
I have came to know from many books that the isotherm fails at high temperature.
According to Freundlich at high temp 1/n =0 so extent of adsorbtion is constant or independent of pressure.
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4answers
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Is “stainless” a bulk or a surface property of stainless steel?
In particular, if I cut a block of stainless steel in half, would the newly formed faces be stainless as well?
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Are lypophilic colloids also charged particles
Lypophobic particles of colloid have similar charge because of which they repell each other and stay in the size range of a colloid, do not coagulate to form a suspension. Is something similar also ...
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1answer
59 views
Why does Freundlich adsorption isotherm not have a term for surface area?
Why does Freundlich adsorption isotherm not have a term for surface area?
The formula given by Freundlich adsorption isotherm:
$$ \frac{x}{m}= k P ^{1/n}$$
Where $x$ is the mass of gas adsorbed ...
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2answers
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How to remove stain from pavement after having dropped sulfuric acid on it?
I had this car battery that flipped in my car trunk.
When I got it out of there it spilled some acid on the pavement. It's a sulfuric acid battery. I added some baking soda on it and poured some more ...
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19 views
Image formation in LEEM
currently I'm studying for my master's examination in physical chemistry. The topic will be surfaces and catalysis. To prepare myself I'm reading "Surface Science - An introduction" by Oura. ...
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Is it possible to reduce the desorption temperature of an adsorption/desorption reaction by changing (decreasing) the pressure?
I am studying about zeolite/water adsorption beds and need to see if there is a way to tune the desorption temperature. Ideally, I need to reduce the desorption temperature. Is it possible to do this ...
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2answers
108 views
How to reduce surface tension of oil?
I would like to create tiny colored drops slowly falling down in a transparent liquid.
The diameter of the droplets must be around 2mm, and their speed must be approximately 0.5 mm / sec.
For that, ...
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Can pi backdonation occur on non-metal centers?
The common example of back-donation is the interaction of a CO molecule with a metal center (d-orbitals) on a surface.
Can a similar mechanism occur between CO and a non-metal center, like oxygen on ...
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1answer
90 views
What are molecular species?
I am a highschooler learning about adsorption for the first time.My school textbook says--
"The accumulation of molecular species at the surface rather than
in the bulk of a solid or liquid is ...
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30 views
Properties of Nanocar racetracks
In the Nanocar race competition the molecules are raced on a gold surface.
Is there a specific property of gold that it forms a good "racetrack"? On what criteria does it compare with other metal ...
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1answer
30 views
What decides the nature of emulsifying agents?
I read
The emulsifying
agent forms an interfacial film between suspended particles and the
medium. The principal emulsifying agents for O/W emulsions are
proteins, gums, natural and ...
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119 views
Calculating pre-exponential factor using transition state theory
I would like to calculate the pre-exponential factor of a surface reaction using transition state theory. I've seen two ways to calculate it but I get different answers for each method (and I don't ...
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111 views
Helmholtz double layer
I don't quite understand what is meant by the Helmholtz double layer.
Textbooks states something along the lines of:
the colloidal particles attain charge by selective adsorption, due to
this it ...
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0answers
29 views
How do lyophilic sols protect lyophobic sols?
How are lyophobic sols prevented from coagulating when lyophilic sols are added to them? I tried to search for the answer but didn't get a plausible explanation anywhere.
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2answers
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Surface Chemistry - Dipole Moment of Surfactant with Water and Phases of a Monomolecular Layer
Recently, I have been trying to study surface chemistry and I have come across questions that I do not understand how to answer. I understand what a dipole moment is, defined as a charge separation ...
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0answers
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3D printing of alumina
I want to print a structure of alumina, and the 3D printer that I am using is an extrusion-based printer. So I need your help in knowing that what composition (binders and deflocculant) of alumina ...
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4answers
166 views
Where does the potential energy of capillary action come from?
Capillary action is when water pulls itself up a paper towel, glass tube or a tree. It is going up, which results in an increase in potential energy. According to the law of conversation of energy, ...
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1answer
72 views
Adhesion of polymerized fats to cast iron
I'm trying to make an informed decision as to which oil is best to use for cast iron seasoning. I've read all kinds of conflicting information online and the only consistency seems to be that ...
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1answer
51 views
Why does the surface of an acid appear to have a stronger “dissolving power”?
In this Periodic Videos YouTube video by Brady Haran and the University of Nottingham, we see a piece of gold being dissolved in aqua regia, while Professor Poliakoff explains why aqua regia can ...
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Computational method to model the interactions between a liquid, a solid surface and particles on it?
I’m looking for a way to model the interactions between a liquid, a surface and various particles over the surface, in order to simulate the cleaning of said surface with different substances.
My ...
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0answers
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Why are lyophillic sols uncharged and lyophobic sols charged?
Gums, resins, glue, gelatin starch are uncharged and lyophillic where as metal sulphides and hydroxides are charged and lyophobic.
Right after studying o-chem this seemed quite contradictory as ...
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1answer
336 views
How does critical temperature affect adsorption?
I don't really understand how does a high critical temperature favour adsorption?
What I think is that the lower the temperature, more easy is it for the gas to liquefy and therefore adsorption is ...
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1answer
137 views
Why do bubbles form on the side of a plastic bottle?
I have a plastic bottle filled with drinking water where only one side of the bottle has air bubbles. I know that water is not pure and there are dissolved gases, and my theory is that there are small ...
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1answer
61 views
How can I make an alloy wetter?
I'm trying to make a Bismuth-Indium based low-melt alloy wetter (specifically, better at wetting to solid metals and glass). I've tried adding gallium, which obviously works, but due to its metal-...
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119 views
What is the effect of temperature changes on rate of chemisorption?
In chemisorption, if temperature increases, then after some time why does its rate decrease? I tried to explain it by Le Chatelier's principle but I don't believe it's valid as chemisorption is ...
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9answers
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Would it be possible to destroy gold?
I'm a writer. I have a scenario in which a sizable amount of gold needs to be rendered unusable, preferably completely destroyed. I know an acid like aqua regia is able to dissolve gold, but would ...
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1answer
58 views
Is it possible to prevent agglomeration and sedimentation of microparticles just by increasing the viscosity of the medium?
I am considering a suspension of a fine powder in a high-viscosity liquid. The suspension shall be stable over long time scales, i.e. the particles only move a few mm per year, and I have the ...
2
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0answers
27 views
Phosphonate reaction with oxides and their stability?
I have read some papers stating that $\ce{SiO2}$ surfaces can bind phosphonates, but in water they hydrolyse. However, for $\ce{Si}$ surfaces, they are stable in water. In both cases, the reaction ...
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0answers
29 views
Capillary forces in horizontal plane
In a physical chemistry course, we went to the lab and made a microstamp out of an elastomer. This stamp has gaps of 25 µm in width. When the elastomer had hardened, we placed it on a microscope slide ...
2
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1answer
65 views
A question about “post it note”
I dipped a sticky note in water and there was a clear difference between the water absorption in the area with glue and the one without glue. The area with glue was more damp than the one without it. ...
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0answers
54 views
Computational modeling of steric repulsion between two polymer mediated magnetic Nanoparticle?
Can you recommend any modern article or research papers on steric interactions and forces between two or multiple magnetic nanoparticles with polymer brushes in a nonpolar solvents? something with ...
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1answer
514 views
Activation energy in physical adsorption
Physical adsorption of molecules on surface requires activation energy, because bonds of the adsorbed molecules are broken.
Is this a valid statement?
I have been under the assumption that physical ...
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1answer
368 views
Does BET theory apply to type H3 and H4 isotherm for calculating surface area? [closed]
BET applies to type 2 and 4. That is basically unanimous.
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1answer
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Influence of vapor pressure on surface tension
How does a liquid's vapour pressure affect its surface tension?
i.e. to say, if a liquid's vapour pressure increases, will the surface tension increase or decrease?
The SERP for this question yields ...
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56 views
Reaction Kinetics and Catalyst Addition
The addition of a catalyst is known to increase the rate constant of a reaction by providing an easier pathway for the reaction to occur, one with lesser activation energy.
My doubt is:
Is it ...
3
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1answer
465 views
Auto-catalysis Mechanism
I just read about the theory of auto-catalysis, and here's one thing which is sort of unclear to me:
In this type of catalysis, one of the reaction product catalyses the reaction. For example, in ...
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1answer
428 views
“Nitrogen (gas) is physisorbed over iron (metal) at room temperature”: Is this for real? [closed]
My copy (PDF) of Levine's Physical Chemistry (6th ed.), page 570-571, section: "Adsorption of Gases on Solids", states:
Physical adsorption is nonspecific. For example, $\ce{N2}$ will be physically ...
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1answer
64 views
How to avoid oxidation of Si using a sub nanometer layer
Does anyone know how and which material to use to protect a Si layer from Oxidation by a small layer of thickness less than 1 nm ? (probably using atomic layer deposition)
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What system of nomenclature can I use to indicate the positions of specific kinds of atoms of a surface reconstruction?
I was reading a journal based on SiC reconstructions, and they seem to mention that every dangling bond in the $(1\times 1)$ unreconstructed Si face or the $(0001)$ direction bonds up with a Si adatom ...
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1answer
254 views
When using LPCVD, is it possible to pattern a silicon wafer with poly-silicon using a mask?
I know it's possible to etch (i.e. pattern) poly-silicon, but I'm curious if one can just use a mask instead. Are there masks that inhibit the growth of poly-silicon?
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1answer
189 views
Is the surface of glass a fine layer of silanol?
Today we learned in class through a vivid demonstration that water sticks to glass. We were then taught that water sticks to glass because while glass is mainly composed of silicon dioxide, the ...
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1answer
4k views
What is the difference between BET and Langmuir model for calculating the specific surface area?
Brunauer–Emmett–Teller (BET) surface area is measured by specific surface area of the adsorbent. BET surface area is measured by using non-corrosive gases like $\ce{N2}$, $\ce{CO2}$, $\ce{Ar}$ etc. ...
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0answers
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Can negative adsorption be considered equal to sorption?
In my book it was written sorption is basically when the substance gets uniformly distributed into the bulk of the solid but at the same time its concentration is higher at the surface then in the ...
5
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1answer
228 views
What, if any, are the differences between hemiwicking and wicking?
I'm encountering these two terms, but their uses seem to be different, and there's little documentation out there defining the terms.
Here is an example definition I've found of Wicking:
Wicking ...
3
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1answer
819 views
What is the definition of porous materials?
Is there a consensus on scientific definition of porous materials? There are many definitions out there which do not seem accurate enough:
from wikipedia (accessed July 2017):
A porous medium or a ...
2
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1answer
349 views
How can I measure a droplets contact angle without a setup?
I have to use a phone camera to replicate the Sessile drop analyzer, but there doesn't seem to be a standard to different parameters, such as how far away should my camera be from the droplet or how ...
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Functionalizing CTAC stabilized nanoparticles
I am working on functionalizing silver-gold bimetallic nanoparticles. My nanoparticles are stabilized by CTAC(cetyltrimethylammonium chloride).The most articles which I found, are about the ...
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1answer
305 views
Substances comprised of large molecules are liquids at room temperature?
I am looking for compounds that are liquid at normal temperatures and are physically very large, to be used in an ellipsometer adsorption experiment. I am currently working with decane. The candidates ...
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1answer
118 views
How does water freeze and crystallize on a cold superhydrophobic surface?
Superhydrophobic surfaces are nano-structured to "repel" liquid water and there has been a lot of work done to understand the microscopics of wetting of these nanostructures.
What I currently am ...
