Colloid chemistry - the science that studies the methods of producing the composition, internal structure, chemical and physical properties of disperse systems.Disperse Systems - are systems that are composed of crushed particles (discontinuous phase) dispersed in ambient (dispersed) medium: gases, liquids or solids.Particle sizes of the dispersed phase (crystals, droplets, bubbles) differ in the degree of dispersion, the magnitude of which is directly proportional to particle size.In addition, the dispersed particle differ in other characteristics, usually the state of aggregation of the dispersed phase and the environment.
dispersions and their classification
All variance of the particle size of the dispersion phase can be classified into molecular ion (less than one nm), colloid (from one to one hundred nanometers), coarse (more than one hundred nanometers).
Molecular dispersion systems. These systems contain particles whose size is less than one nm.This group includes a variety of true solutions of non-electrolytes: glucose, urea, alcohol, sucrose.
coarse systems are characterized by the largest particles.These include emulsions and suspensions.Disperse systems in which the solid is localized in a liquid dispersion medium (a solution of starch, clay) are referred to as suspensions.Emulsions - are systems that are prepared by mixing two liquids, wherein one in the form of droplets dispersed in the other (oil, toluene, benzene, water or a droplet of triacylglycerols (fat) in the milk.
Colloidal dispersion systems . Theysize colloidal particles up to 100 nm. Such particles can easily penetrate the pores of the paper filter, however, do not penetrate through the pores of the biological membranes of plants and animals. Since the colloid particles (micelles) are electrocharge and solvent ionic membranes, through which they remain in a suspended state, theyquite a long time can not precipitate. A striking example of colloidal systems are solutions of gelatin, albumin, gum arabic, colloidal solutions of gold and silver.
degree of dispersion allows to distinguish between homogeneous and heterogeneous dispersions. In homogeneous disperse systems phase particles milled to molecules, atoms,and ions.Examples of such dispersions can be dissolved in water, glucose (molecular dispersion) and cooking salt in water (ion-dispersion).They are the true solutions.Molecular size of the dispersed phase is less than one nanometer.
Disperse systems and solutions
Of all the systems and solutions in the life of living organisms, the most important are colloidal dispersions.As is known, the chemical basis for the existence of a living organism is the exchange of proteins therein.The average concentration of proteins in the body is from 18 to 21%.Most proteins are soluble in water (the concentration of which in humans and animals is approximately 65%) and form colloidal solutions.
There are two groups of colloidal solutions: liquid (sol) and gel (gels).All the vital processes occurring in living organisms associated with colloidal matter.In every living cell biopolymers (nucleic acids, proteins, gikozaminoglikany, glycogen) are in the form of dispersed systems.
Colloidal solutions are widespread and inanimate nature.Such solutions include oil, fabrics, plastics, synthetic fibers.Many foods include colloidal solutions: yogurt, milk, etc.Most drugs (serum, antigens, vaccines) are colloidal solutions.Include colloidal solutions and paints.
