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When lyophilic sols are added to lyophobic sols, depending on their sizes, either lyophobic sol is adsorbed in the surface of lyophilic sol or lyophilic sol is adsorbed on the surface of lyophobic sol. The layer of the protective colloid prevents direct collision between the hydrophobic colloidal particles and thus prevents coagulation. [1]
The gold number is the minimum weight (in milligrams) of a protective colloid/lyophilic colloid required to prevent the coagulation of 10 ml of a standard hydro gold sol when 1 ml of a 10% sodium chloride solution is added to it. [1] It was first used by Richard Adolf Zsigmondy in 1901.
A sol is a colloidal suspension made out of tiny solid particles [1] in a continuous liquid medium. Sols are stable, so that they do not settle down when left undisturbed, and exhibit the Tyndall effect, which is the scattering of light by the particles in the colloid. The size of the particles can vary from 1 nm - 100 nm.
Particle agglomeration can be a reversible or irreversible process. Particle agglomerates defined as "hard agglomerates" are more difficult to redisperse to the initial single particles. In the course of agglomeration, the agglomerates will grow in size, and as a consequence they may settle to the bottom of the container, which is referred to ...
A and B can react to form C and D or, in the reverse reaction, C and D can react to form A and B. This is distinct from a reversible process in thermodynamics. Weak acids and bases undergo reversible reactions. For example, carbonic acid: H 2 CO 3 (l) + H 2 O (l) ⇌ HCO 3 − (aq) + H 3 O + (aq).
Unlike solutions and colloids, if left undisturbed for a prolonged period of time, the suspended particles will settle out of the mixture. Although suspensions are relatively simple to distinguish from solutions and colloids, it may be difficult to distinguish solutions from colloids since the particles dispersed in the medium may be too small ...
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 , [ 1 ] while others extend the definition to include substances like aerosols and gels .
The sol–gel approach is a cheap and low-temperature technique that allows the fine control of the product's chemical composition. Even small quantities of dopants, such as organic dyes and rare-earth elements , can be introduced in the sol and end up uniformly dispersed in the final product.