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 four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structur ...

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, ...

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 cir ...

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 compou ...

ed ink, 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. 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 Bredig's arc method or electrical disintegration is a method of preparation of colloidal solution, of metals such as gold, silver or platinum. This method consists of both dispersion and condensation. An arc is struck between electrodes of the de ...

. 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'' * ''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''

References

Colloids Colloidal chemistry {{Chem-stub

See also

References