Questions tagged [colloids]
A colloid is a substance in which microscopically dispersed insoluble particles are suspended throughout another substance.
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How can gelling agents "dissolve" in the liquid phase as a "colloid" mixture?
Gelling agents according to Wikipedia:
Some thickening agents are gelling agents (gellants), forming a gel, dissolving in the liquid phase as a colloid mixture...
But colloid according to Wikipedia:
...
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Weirdness From Boiling Gold Colloid Dry
I was doing an experiment in my chemistry class and found something odd.
We prepared a colloid of gold with the following procedure.
1: Measure out 20ml of Hydrogen Tetrachloroaurate (iii) in grad ...
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Temperature and zeta potential
What is the temperature effect on zeta potential?
My problem was assigned by my teacher for the final exam preparation: "When the temperature is increased, and given in this temperature range, ...
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Co(NO3)2 forming colloid in H2O, and Methanol
I was just trying to make a stock solution of some Co(NO3)2 . One in H2O, another in Methanol. Both don't completely dissolve. They're almost dissolved and appear near translucent but when shining a ...
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Why is micelle formation endothermic?
Most websites mention that it is endothermic and some mention that it is endothermic at low temp. and exothermic at high temp. Nor do I know the correct answer neither I can guess the reason for any ...
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Watercolor pigment conundrum - can a change in ionic profile induce flocculation?
A client of mine has installed an ion exchange water purifier to de-harden her tap water. After that, however, she noticed that it has negatively affected her watercolor painting. From what she ...
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Charge acquired by sols after their preparation
This table from my textbook (p. 20), shows nature of charge on particles of listed sols, in their original or natural form. What reasons can be attributed to oxides (sols) being positively charged? ...
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How do clay particles form a colloidal mixture?
I have been learning about water coagulation in my chemistry textbook. Apparently, before being treated, water has clay particles, primarily silicates and aluminosilicates, which apparently have a ...
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What kind of solution is formed when alkali metals are dissolved at high concentration in liquid ammonia?
When an alkali metal is dissolved in liquid ammonia, it results in the formation of a deep blue coloured solution. $$\ce{M + (x + y) NH3 -> M+(NH3)_x + e^-(NH3)_y}$$
The ammoniated electrons absorb ...
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Why can't there be a gas-dispersed-in-gas colloid? [closed]
Colloids, a special type of heterogeneous mixtures, typically have two components. One is the dispersed phase (DP), which is the "solute-like" part and another one is the dispersion medium (...
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Name of particles in a suspension
What is the proper name given to the particles in a suspension? Suspensae perhaps? When these particles are brought out of suspension, and precipitate down to the bottom of the mixture, what is that ...
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DLVO Theory of Colloid Stability
DLVO theory gives the curve of potential energy vs distance of two colloid particles. Potential energy curve is derived for colloids being only electrostatically stabilized and not sterically.
Looking ...
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Why do silver halide crystals in suspension, develop a surface charge
This is a question related to analog photography. Photographic films have a suspension of silver halide crystals in them, and these crystals have adsorptive properties which are used in this ...
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Bond-order parameter $g_6(r)$
I would like to know the explicit steps to compute the bond correlation function
$$g_6(r) = \langle\Psi_6^*(0) \cdot \Psi_6(r)\rangle$$
for colloids in my experiment (2D). I have the position of all ...
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Will a liquid-liquid emulsion and the separated emulsion have same volume?
Let's assume that there is no dispersed gas (bubbles). Not sure about dissolved gas; maybe you can tell me if that matters. Ordinary liquids (aqueous solution and biological oil). Surfactants are ...
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What allows for colloidal solutions of polymers to act like solutions despite the large size of polymers?
I have been introduced to a paragraph in my textbook that I am trying to understand.
Macromolecular colloids: Macromolecules in suitable
solvents form solutions in which the size of the ...
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Why are colloidal sol particles of acidic dyes negatively charged and basic dyes positively charged, when it should be the other way round?
From NCERT Class 12 Chemistry; Sri Aurobindo Marg, New Delhi, India; January 2019; p. 136:
Colloidal solutions of basic dyes like methylene blue are positively charged whereas colloidal solutions of ...
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Why is there preferential adsorption of a common ion during preparation of colloids by peptization?
There was a similar question asked here on Chem SE, but the answer was not very satisfactory to me, so I am asking a fresh question.
Peptization is the process of creating a colloid from a precipitate ...
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Brownian motion of asymmetric particles
The classic Stokes-Einstein relation ($D=k_BT/(6\pi\eta r)$) it is assumed that the particle undergoing Brownian motion is spherical, and experiences ordinary Stokes flow between (or during) ...
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How practically to determine dispersion's Hamaker constant using CCC?
I know that Hamaker constants can be determined from CCC data.
$$ccc=\frac{9.85 \cdot 10^4 \epsilon^3 k_B^5 T^5 \gamma^4}{N_A e^6 A^2 Z^6}$$
Where, $\epsilon$ is solvent dielectric constant, $N_A$ is ...
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Do lyophilic sols have an electrical double layer?
"There are two factors which are responsible for the stability of lyophilic sols. These factors are the charge and solvation of the colloidal particles".
Quoted from NCERT book of OC
But we ...
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Particle tracking in colloids and uniformity in fractional part function
I don't know if its right place to ask this question since chemistry and programming both are involved.
I was working on particle tracking of series of pictures (.tiff) of colloids. And I was Using ...
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How do lyophilic colloids reduce surface tension?
It's given in my textbook that the surface tension of lyophilic/hydrophilic solutions is lower than water.
But my intuition says, since in lyophilic solutions the interaction between a lyophilic ...
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When is it realistic to model diffusion without advection?
Brownian motion abounds in nature, but so does drift current. In theoretical models of solutions and colloidal suspensions it is sometimes assumed that advection is negligible. I'm wondering if this ...
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Why are nanoliposome encapsulated antibiotics still so unavailable despite being so effective?
I wasnt sure how the phrase the headline question really nor if this is the right place to ask it, but i'm primarily interested in the chemical synthesis aspect and the experience of chemists ...
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Are the particles of a colloid "solid"?
I want to understand what are the particles of a colloid in the microscopic scale. According to Wikipedia:
A colloid is a phase separated mixture in which one substance of
microscopically dispersed ...
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How to prevent sedimentation of an EDTA suspension?
I tried to create a suspension of EDTA powder in glycerin with 1:1 ratio. I keep facing problem of EDTA sedimentation. I've tried other ratios also but this was the only one which formed least amount ...
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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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Actual color of colloids [closed]
I have read that the color of colloid depends upon the wavelength of light scattered by the dispersed phase and also in the sense in which the receiver receives the light.
If all of this depends on ...
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Boilling colloidal silver?
I have some colloidal silver that i bought from a shop. It is 18ppm, however, I need a higher PPM and I can't seem to buy it anywhere where I live.
If I boil this colloidal silver, would it make the ...
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How does total depth affect the colloid gradient?
When a colloid reaches diffusion–sedimentation equilibrium, it creates a gradient where the solute concentrates toward the surface or the bottom of the vessel based on its density relative to the ...
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Colligative properties of colloids [closed]
The following lines are from my textbook:
Colloidal particles being bigger aggregates, the number of particles in a colloidal solution is smaller than a true solution. Hence, the values of ...
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How does adding HCl convert AgCl into a sol?
According to the text I follow, in peptization the ions of the added electrolyte (peptizing agent) get adsorbed by the particles of the precipitate and turn the precipitate into a sol. An example of ...
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Why does a low concentration of soap in water behave as a strong electrolytes?
According to my text, "a colloid in which the dispersed phase consists of micelles is called an association colloid." An example would be soap in water. They use the term 'associated colloid' and '...
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Why does Tyndall scaterring produce conical shape?
When light is passed through a collidal solution, due to Tyndall scattering, the path of light appears to be a bright cone. Why does it have to form only a conical shape?
The conditions for Tyndall ...
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hydrodynamic thickness of polymer vs. concentration of electrolyte?
I've measured the hydrodynamic thickness of a NaPSS layer on polystyrene latex and plotted it against the concentration of the supporting electrolyte, NaCl.
My graph shows a general decrease in ...
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Estimating maximum size of magnetite particles in this Nile Red ferrofluid video?
In the Nile Red video Making ferrofluid from scratch a suspension of small magnetite ($\ce{Fe^{2+}Fe_2^{3+}O_4^{2−}}$) particles is produced from a combination of ferrous chloride and ferric chloride.
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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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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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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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Gelifying hydrogen peroxide
What substances could be used to gelify 60% hydrogen peroxide? I imagine anything organic like agar would be broken down by the radicals. I tried looking up what dentists use and the only thing that ...
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Is it possible to make micelles to pick up Microplastics from water?
I'd like to know if I could get micelles to pick up microplastics in water. I read that microplastics are sometimes charged, so can we make the lyophobic end to pick up microplastics, so that they can ...
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How to charge titanium dioxide particles for a DIY e-paper capsule? [closed]
I'm trying to make a single e-paper capsule (1 cm × 1 cm) at home. At first, I tried to charge the $\ce{TiO2}$ particles by putting them in $\ce{H2O}$ with $\ce{NaOH}$ and then putting that whole ...
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Generating colloids / nano-particles from palladium and platinum wire
I know I can generate colloidal silver from the following link
generate colloidal silver
I now have 2 palladium and 2 platinum wires and would like to make one colloidal solution of palladium and one ...
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Why do old black and white photos fade?
I understand why photos based on organic dyes would fade (discussed previously). But photos based on metallic silver fade as well such as like the one shown below. As a metal (a fairly stable one at ...
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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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Why do properties of colloidal solution depend only on dispersion medium's physical state? [closed]
According to a past year JEE question, properties of colloidal solution depends only on dispersion medium's physical state and not on nature of dispersed phase or dispersion medium, or temperature of ...
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Why does the colour of gold sol change with particle size? [duplicate]
Regarding the colour of gold sol, my book says
Finest gold sol is red in colour; as the size of particles increases, it appears purple, then blue and finally golden.
This is the image I found on ...
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Colour of colloids
Why colours of colloidal solutions are different when viewed along different directions?
For example Milk appears blue when viewed by reflected light and red when viewed by transmitted light
Is it ...
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Dependence of Osmotic Effects on Particle Size
van't Hof's equation for osmotic pressure is derived with the assumption, among others, that the particle size of the solute is comparable to the particles size of the solvent. It holds well so long ...
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