A sol is a
colloid
A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend ...
al suspension made out of tiny
solid
Solid is one of the State of matter#Four fundamental states, four fundamental states of matter (the others being liquid, gas, and Plasma (physics), plasma). The molecules in a solid are closely packed together and contain the least amount o ...
particles
in a continuous
liquid
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
medium. Sols are stable and exhibit the Tyndall effect, which is the scattering of light by the particles in the colloid. Examples include amongst others
blood
Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...
,
pigment
A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...
ed
ink
Ink is a gel, sol, or solution that contains at least one colorant, such as a dye or pigment, and is used to color a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, reed pen, or quill. Thicker ...
, cell fluids,
paint
Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture. Paint can be made in many ...
,
antacids
An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion or an upset stomach. Some antacids have been used in the treatment of constipation and diarrhea. Marketed antacids contain salts of alu ...
and
mud
A MUD (; originally multi-user dungeon, with later variants multi-user dimension and multi-user domain) is a Multiplayer video game, multiplayer Time-keeping systems in games#Real-time, real-time virtual world, usually Text-based game, text-bas ...
.
Artificial sols can be prepared by two main methods: dispersion and condensation. In the dispersion method, solid particles are reduced to colloidal dimensions through techniques such as
ball mill
A ball mill is a type of grinder used to grind or blend materials for use in mineral dressing processes, paints, pyrotechnics, ceramics, and selective laser sintering. It works on the principle of impact and attrition: size reduction is done ...
ing and
Bredig's arc method. In the condensation method, small particles are formed from larger molecules through a chemical reaction.
The stability of sols can be maintained through the use of dispersing agents, which prevent the particles from clumping together or settling out of the suspension. Sols are often used in the
sol-gel process, in which a sol is converted into a gel through the addition of a crosslinking agent.
In a sol, the dispersed phase is typically solid and the continuous phase is typically liquid. This is the opposite of an emulsion, in which the dispersed phase is typically liquid and the continuous phase is typically solid or semi-solid.
Properties of a Colloid (applicable to sols)
* ''
Heterogeneous Mixture
In chemistry, a mixture is a material made up of two or more different chemical substances which are not chemically bonded. A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the ...
''
* ''Size of colloid varies from 1 nm - 100 nm''
* ''They show the Tyndall effect''
* ''They are quite stable and hence they do not settle down when left undisturbed''
See also
*
Brownian motion of sol particles
References
Colloids
Colloidal chemistry
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