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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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
9 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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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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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
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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
35 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
42 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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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
78 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
32 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
54 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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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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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
54 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 ...
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26 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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1answer
64 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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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
315 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
243 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
1k views
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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37 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 ...
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1answer
313 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
241 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
51 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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249 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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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
3k 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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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 ...
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1answer
175 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 ...
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1answer
571 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 ...
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1answer
268 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
247 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
101 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 ...
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101 views
Conductive hydrophobic material
I was looking for a conductive hydrophobic material if there is one? If not why? I was researching and I found some material about laser etching on metals that causes superhydrophobicity but that I ...
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1answer
44 views
Crystallisation and crystal surface
It is my understanding that if you put table salt (as an example of polar compound) in water, the Na+ and Cl- ions will freely move through the solution. They will make the solution conductive and ...
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2answers
229 views
Mixing water and oil in microgravity outside of a container
What would happen if I where to mix water and oil in a vacuum in microgravity where the temperatures were low enough so that the oil and water remain liquids also, the mixture is not inside of a ...
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2answers
101 views
How does physical adsorption of mixed gas occur on solid? (eg I mean how the gas molecules of compete each other for a slot on solid surface)
I am working on sorption phenomenon of gases (including inert gas) on coal seam surface.
For a mixture of 2 gases at a certain pressure, carbon dioxide and methane, for instance, $\ce{CO2}$ is ...
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0answers
118 views
Very fast brass oxidation
I work for a company that manufactures pyrotechnics for the oil and gas industry, and we have been having an odd phenomenon occur.
One part, a brass tube with a copper clip filled with black powder, ...
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2answers
395 views
How fast a surface oxide layer is formed on bulk chromium?
If a chromium piece is cut in half, how long would it take for an oxide layer to form on the new surface (room temperature)? i.e. is it a matter of seconds/minutes/hours/days/weeks?
The closest study ...
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0answers
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How to create a Non Water loving Vegatable Oil Foam?
I am trying to create a vegetable oil foam (or large quantity of air bubbles) and as I am not a Chemist by far.
First I was thinking of using Amphiphilic surfactant, but I don't want this foam to be ...
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169 views
Transition state optimisation on the surface of periclase
I want to model a reaction catalysed by periclase ($\ce{MgO}$) using DFT.
I have a good guess on the transition state (TS) of the reaction that goes in gas phase/solvent (produced using MOPAC).
The ...
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1answer
147 views
What is a typical monolayer formation time for liquid phase adsorbate on a solid surface?
Let's say a solid is submerged in a solution of species with functional groups and a self-assembled monolayer is forming. What are the typical time scales for the formation of a continuous monolayer? (...
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127 views
What is the surfactant's role in the non-coalescence of water droplets?
I have recently seen many videos that talk about the noncoalescence of water droplets; however, I do not understand the purpose of adding surfactants into the water. From my knowledge (high school), ...
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558 views
Why non polar liquids wet non polar surfaces better than polar surfaces?
In semiconductor industry adhesion promoters (such as HMDS) are applied on various surfaces to improve adhesion between the surface and the photoresist:
On SiO2 and many metals surfaces, the air ...
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Surface Tension and Evaporation
Why does acetone evaporate faster than ethanol yet still has a higher surface tension?
I would expect it to have a lower surface tension... I got the data from surface-tension.de.
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1answer
958 views
What is the chemical structure of ceramic nonstick coating on pans?
There are lots of pans nowadays that have a ceramic nonstick coating instead of a PTFE coating. However I can not find anything online describing what kind of ceramic such nonstick coatings are. Does ...
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2answers
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Overall equilibrium expression for competitive equilibria
I have a case where I have two reactions that depend on a common reactant. The reactions can be written as:
I) $\ce{A + B <=> AB}$
II) $\ce{A + C <=> AC}$
We can thus write equilibrium ...
