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 makes a colloid particles lyophilic or lyophobic?
Why do some colloids don't precipitate(lyophilic) and some do(lyophobic)? Why is gold lyophobic, why does it need protective colloids also why does NaCl cause precipitation in gold sol?
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Difference between vapor-phase transport and vapor-phase deposition?
I am currently studying the textbook Physics of Photonics Devices, Second Edition, by Shun Lien Chuang. In a section discussing The Invention of Semiconductor Lasers, the author says the following:
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Electric double layer formation
What textbook states about the formation of electric double layer:
When silver nitrate solution is added to potassium iodide solution the precipitated silver iodide adsorbs iodide ion from ...
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51 views
What is the logic behind the terminology lyophilic and lyophobic colloids?
Its given in my text book that-
Colloidal dispersions of starch,rubber,proteins etc are lyophilic colloids whereas colloidal dispersions of metals,sulphides etc are lyophobic in nature.
But even ...
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91 views
Hardy Schulze Rule
There was a question which was asked in JEE Main 2020 held on 8th January. The question was:
As per Hardy–Schulze formulation, the flocculation values of the
following for ferric hydroxide sol ...
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166 views
Why Freundlich adsorption isotherms fails at high pressure conditions?
Experimentally it was determined that extent of gas adsorption varies directly with pressure, and then it directly varies with pressure raised to the power 1/n until saturation pressure Ps is reached. ...
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Surface energy for different crystallographic planes
For a given crystal structure, say body centred cubic, on what factors does surface energy of each plane depend?
A basic approach considers the atomic density on each crystallographic plane, the ...
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1answer
23 views
Acid-Temperature coagulation of milk
I was making coffee with a cup of boiling milk which was 2 days old. I used instant coffee powder and some sugar for the making of it. Tried to make a very hot coffee but usually prefer medium hotness....
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1answer
33 views
Is activated charcoal an air purifier?
It's well known that activated charcoal is an adsorbent and due to very big surface area per unit of mass it can adsorb a lot of particles.
Let's take as an example for my question this product on ...
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46 views
Relation between rate of adsorption and the critical temperature of a gas [duplicate]
How is the rate of adsorption related to the critical temperature of a gas? My textbook says more the critical temperature, better are they adsorbed. But I cannot really understand why. They threw in ...
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Does Coagulation depends on nature of Electrolyte?
I am not talking about Hardy Schulz Rule .
Suppose if i add an electrolyte to a colloidal solution. If that electrolyte contain same ion that of colloidal particle due to preferential adsorption is ...
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Mechanism of Peptization [closed]
Can somebody please explain the mechanism of Peptization(or give a link to the website which explain the mechanism step by step). The Mechanism given in my book is somewhat different from the ...
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Epoxy-silane-coated glass applications or the preparation or quality control for the silanized glass
The task is to make myself (3-Glycidyloxypropyl)trimethoxysilane (GMPTS for short) covered microscope slides to immobilize antibodies.
Each time I cover the freshly prepared slide with Ab, I get ...
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1answer
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Does bicarbonation require water?
In an aqueous solution of $\ce{NaOH}$ exposed to the atmosphere one can probably expect some degree of $$\ce{NaOH(aq) + CO2(g) -> NaHCO3 (aq)}$$
But, what would happen if just a solid block of $\...
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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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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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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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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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290 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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118 views
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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620 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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1answer
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Nanocar racing competition and the race tracks used
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
44 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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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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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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2answers
73 views
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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1answer
39 views
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
556 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
145 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
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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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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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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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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
78 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
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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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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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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 ...
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1answer
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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
757 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
499 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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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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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
671 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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652 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
81 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)
