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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How lyophilic colloids reduce surface tension?
Its given in my textbook that surface tension of lyophilic/hydrophilic solution is lower than water.
But my intuition says,since in lyophilic solution the interaction between a lyophilic colloid and ...
2
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1answer
34 views
How thick is the colored oxide layer on heat treated stainless steel?
When stainless steel is welded, or just heat treated, it will develop a thicker oxide layer, which in some cases is is rainbow colored, but can become so thick as to appear almost black. From the ...
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1answer
43 views
Viscosity at CMC
What happens to viscosity at critical micelle concentration? Does it increase or decrease abruptly, and if so, what's the reason behind it?
I'm aware of changes in other properties such as ...
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12 views
Relationship between surface energy of liquid and solid states
I have been experimenting with different kinds of hot-melt (hot glue) adhesives. I have been comparing EVA to acrylic on various substrates. In comparing the two I have found the acrylic to be ...
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14 views
Sticking coefficents for dissociative adsorption
I am trying to simulate the decomposition of Hydrogen Peroxide ($\ce{H2O2}$) on $\ce{Pt}$ using Chemkin Pro. I am using a two step global reaction model for the reaction which is as follows-
$$\ce{...
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1answer
65 views
Why does rate of chemisorption decrease with increase in pressure?
My textbook says that rate of chemisorption decrease with increase in pressure.
I do found a similar statement on the web but couldn't understand this.
The rate of chemisorption depends on the flux ...
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31 views
How does soap actually reduce surface tension of water
I was a bit confused on how soap reduce surface tension of water.I've read some answers like Why does soap reduce surface tension of water and Why do surfactants lower the surface tension
But the ...
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36 views
How stable are surfaces functionalized with APTES?
I'm wondering specifically about magnetite micro particles functionalized/silanated with (3-aminopropyl)triethoxysaline (APTES), though I assume the stability would be the same for most surfaces.
By ...
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23 views
How is ECR (Electron Counting Rule) done in a structure?
I've been told how to apply the ECR to GaAs{001}(2×4) in my lectures but it makes no sense to me and I don't seem to be able to find any other sources that explain this. (This is a further question on ...
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35 views
Could someone advise me on sources for crystallography and surface sciences?
I'm a physicist learning crystallography and surface science on the side of my research and I came across the concepts: surface reconstruction in hexagonal materials, unit mesh of surfaces, etc.
I was ...
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32 views
Brownian motion modeling of surface reaction
I am interested in simulating a reaction-diffusion system, where particles subjected to Brownian motion can react when they reach a specific surface. The reaction is simple:
A $\rightleftharpoons$ B
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17 views
Change in surface tension of soapy water as oil is added
I am wondering about how the surface tension of clean soapy water changes as oil is added to it? Is the change gradual or is it abrupt as the amount of oil added exceeds the amount of soap available ...
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1answer
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Problem with epoxy silane (Random results in glass silanization). What are crucial points to look at?
I`m trying to immobilize an antibody onto the glass surface by means of GPTOMS (glycidoxypropyl trimetoxy silane). Using the same protocol (silanization in toluene) I get different results any time, ...
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14 views
What is the influence of citrate on PEG-modified polyacrylamide hydrogels?
I've been having a puzzle explaining the experimental results with the citrate anions and PEG modified polyacrylamide:
According to the experimental data there is a hydrogel swelling whenever citrate ...
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0answers
27 views
surface energy versus surface tension and contact angles
I am hoping to measure the surface tension between two fluids (salt water and isopropyl alcohol), by measuring the appropriate contact angles, and applying Young's equation: https://en.wikipedia.org/...
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1answer
173 views
Finding the Freundlich adsorption isotherm from the graph of log(x/m) v/s log(p)
The following problem was asked in JEE Mains 2020 (Sept 2, Shift 1),
The mass of gas adsorbed, $x$, per unit mass of adsorbate, $m$, was measured at various pressures, $p$. A graph between $\log\frac ...
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58 views
Thermodynamics of micellisation
Micellisation is found to be spontaneous i.e. $\Delta G < 0.$ It's found that $\Delta S > 0,$ which was intuitive since, solvated molecules are released. And, it may be most loosely started that ...
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Doubt's regarding inputting surface reaction for Chemkin Pro
I want to simulate the reaction of a mixture of ethanol and Hydrogen Peroxide on $\ce{Pt}$ using Chemkin Pro. I want to create a surface input files which will include surface reaction mechanism of ...
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1answer
36 views
Am I getting the details of mechanism of adsorption right?
Particles on the surface of a substance have a net force towards the geometric center of the substance called residual force.
When molecules come close enough to the surface of a substance the ...
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0answers
49 views
Correlation between redox pseudocapacitance, surface area, and cell potential with metal oxide electrodes
I'm having difficulty intuitively reconciling two different ideas concerning metal oxide thin films in contact with aqueous solutions:
1) that charge storage by both redox pseudocapacitance and ...
2
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1answer
249 views
Why is a drop of chloroform stretched/pulled apart on a water surface?
I distributed drops of chloroform (with a lipid in them) on water (in a Langmuir-Blodgett trough). The chloroform drops form a layer on the water (so that the lipids are distributed on the water ...
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1answer
197 views
Effect of solutes on surface tension
What happens to the surface tension of a solvent, say, water when we mix a solute in it?
For the sake of concrete discussion, the examples that I encountered in a test were sodium chloride $(\ce{NaCl})...
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1answer
80 views
The dissociation of hydrogen on UO2 and PuO2 surfaces: Homolytic or heterolytic?
I have seen that $\ce{H2}$ can dissociate on a metal-oxide surface by two methods:
Heterolytically, forming a proton-$\ce{O}$ bond ($\ce{OH}$ group) and a hydride-metal bond ($\ce{M-H}$) on a metal-...
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1answer
620 views
Chemicals to increase surface tension of water
I want to increase the surface tension of water by 1.2 - 2 times. How about adding one or more chemical substances to the water that can possibily increase its surface tension by the desired amount? ...
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0answers
105 views
Why does silver stick to the glass in Tollens' test? [duplicate]
Why does it not simply form a solid powder at the bottom of the flask?
Does silver also stick to the glass in other silver precipitating reactions?
EDIT:
My question is definitely not the same as ...
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1answer
460 views
Why are van der Waals' forces between gas molecules strong near its critical temperature?
My textbook says
…easily liquefiable gases i.e. with higher critical temperatures are readily adsorbed as van der Waals' forces are stronger near the critical temperatures.
What I do understand is ...
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1answer
41 views
Can Ferrofluids vaporise to gaseous state and Condense back to liquid state and do it many times over? [closed]
Here is the Link for Ferrofluids for basic idea. After going through this Wiki link, probably many people will come to a conclusion like when Ferrofluid boils, its carrier liquid vaporises and nano ...
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20 views
Temperature Programmed Disorption
For second part of the question I'm wondering if the peaks on the right denote the chemisorbed layer, while the peaks on the left denote the physisorbed layers. Since chemisorption results in a ...
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1answer
49 views
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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2answers
618 views
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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0answers
94 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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1answer
444 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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1answer
2k 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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1answer
183 views
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
159 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
103 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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1answer
139 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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0answers
216 views
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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1answer
53 views
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)}$$
But, what would happen if just a solid block of $\...
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4answers
8k views
Is “stainless” a bulk or a surface property of stainless steel?
In particular, if I cut a block of stainless steel in half, would the newly formed faces be stainless as well?
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1answer
167 views
Why does Freundlich adsorption isotherm not have a term for surface area?
Why does Freundlich adsorption isotherm not have a term for surface area?
The formula given by Freundlich adsorption isotherm:
$$ \frac{x}{m}= k P ^{1/n}$$
Where $x$ is the mass of gas adsorbed ...
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2answers
3k views
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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2answers
396 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, ...
12
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0answers
159 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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2answers
2k views
What are molecular species?
I am in high school 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
88 views
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
70 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 ...
3
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0answers
267 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 ...
5
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0answers
357 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 ...
3
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2answers
109 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 ...
