CHEMISTRY GLOSSARY

dissolved substance    →   otopljena tvar

Dissolved substance is a solid, liquid or gas matter dissolved in a solvent. Depending upon the particle size of dissolved substance, solutions differ in properties and can be divided into real solutions (diameter of particles is smaller than 1 nm), colloid solutions (diameter of particles is from 1 nm to 200 nm) and suspensions (diameter of particles is greater than 200 nm).

condensation    →   kondenzacija

1. Condensation is a process of changing from a gaseous to a liquid or solid state, usually done by cooling.

2. Condensation, in colloid systems, is a process where smaller particle join in one colloid size particle

3. Condensation, in chemical terms, is a sort of chemical reaction in which small molecules like water, carbon dioxide, or ammonia single out.

dialysis    →   dijaliza

Dialysis is a method by which large molecules (such as starch or protein) and small molecules (such as glucose or amino acids) may be separated in a solution by selective diffusion through a semipermeable membrane. Through this kind of membrane dissolved particles pass and colloid dimension particles fall behind. For example, if a mixed solution of starch and glucose is placed in a closed container made of a semipermeable substance (such as cellophane), which is then immersed in a beaker of water, the smaller glucose molecules will pass trough the membrane into the water, while the starch molecules remain behind.

electrophoresis    →   elektroforeza

Electrophoresis is a technique for the analysis and separation of colloids, based on the movement of charged colloidal particles in an electric field. The migration is toward electrodes of charge opposite to that of the particles. The rate of migration of the particles depends on the field, the charge on the particles, and on other factors, such as the size and shape of the particles.

Electrophoresis is important in the study of proteins. The acidity of the solution can be used to control the direction in which a protein moves upon electrophoresis.

emulsion    →   emulzija

Emulsion is a colloidal system in which the dispersed and continuous phases are both liquids (e.g. oil in water or water in oil). Such systems require an emulsifying agent to stabilize the dispersed particles.

gel    →   gel

Gels are colloids in which both dispersed and continuous phases have a three-dimensional network throughout the material, so that it forms a jelly-like mass (e.g. gelatine). One component may sometimes be removed to leave a rigid gel (e.g. heating silica gel).

foam    →   pjena

Foams are dispersions of gases in liquids or solids. The gas globule may be of any size, from colloidal to macroscopic, as in soap bubbles. Bakers’ bread and sponge rubber are examples of solid foams. Typical liquid foams are those used in fire-fighting, shaving creams, etc. Foams made by mechanical incorporation of air are widely used in the food industry (e.g. whipped cream, egg white, ice cream, etc.). Foams can be stabilized by surfactants.

indium    →   indij

Indium was discovered by Ferdinand Reich and Hieronymus Theodor Richter (Germany) in 1863. Named after the indicum (colour indigo), the colour it shows in a spectroscope. It is rare, very soft, silver-white metal. Stable in air and water. Dissolves in acids. Metal can ignite and burn. Indium is found in certain zinc ores. Used to coat high speed bearings and as an alloy that lowers the melting point of other metals. Relatively small amounts are used in dental items and in electronic semiconductors.

isoelectric point    →   izoelektrična točka

Isoelectric point (pI or IEP) is the pH of a solution or dispersion at which the net charge on the molecules or colloidal particles is zero. In electrophoresis there is no motion of the particles in an electric field at the isoelectric point. The net charge (the algebraic sum of all the charged groups present) of any amino acid, peptide or protein, will depend upon the pH of the surrounding aqueous environment. For example, alanine can have a charge of +1, 0, or -1, depending on the pH of the solution in which it is dissolved.

lactase    →   laktaza

Lactase is an enzyme that catalyzes the hydrolysis of the disaccharide lactose (milk sugar) to the simple sugars glucose and galactose. Lactose intolerance is the inability to digest lactose. Symptoms can include abdominal pain, abdominal bloating, gas, diarrhea, and nausea.