CHEMISTRY GLOSSARY

chemical weapons    →   kemijsko oružje

The Chemical Weapons Convention, article 2, paragraph 1 defines chemical weapons thus:

Chemical weapons means the following, together or separately:

(a) Toxic chemicals and their precursors, except where intended for purposes not prohibited under this Convention, as long as the types and quantities are consistent with such purposes;

(b) Munitions and devices, specifically designed to cause death or other harm through the toxic properties of those toxic chemicals specified in subparagraph (a), which would be released as a result of the employment of such munitions and devices;

(c) Any equipment specifically designed for use directly in connection with the employment of munitions and devices specified in subparagraph (b).

coenzyme    →   koenzim

Coenzyme is an organic nonprotein molecule, such as a vitamin, that associates with an enzyme in catalysing biochemical reactions. Coenzymes usually participate in the substrate-enzyme interaction by donating or acepting certain chemical groups.

collision theory    →   teorija sudara

Collision theory is theory that explains how chemical reactions take place and why rates of reaction alter. For a reaction to occur the reactant particles must collide. Only a certain fraction of the total collisions cause chemical change; these are called successful collisions. The successful collisions have sufficient energy (activation energy) at the moment of impact to break the existing bonds and form new bonds, resulting in the products of the reaction. Increasing the concentration of the reactants and raising the temperature bring about more collisions and therefore more successful collisions, increasing the rate of reaction.

colloid    →   koloid

Colloids are systems in which there are two or more phases, with one (the dispersed phase) distributed in the other (the continuous phase). Moreover, at least one of the phases has small dimensions, in the range between 1 nm and 1 μm (10^-9 m – 10^-6 m). Dimension, rather than the nature of the material, is characteristic. In this size range, the surface area of the particle is large with respect to its volume so that unusual phenomena occur, e.g., the particles do not settle out of the suspension by gravity and are small enough to pass through filter membranes. Macromolecules (proteins and other high polymers) are at the lower limit of this range; the upper limit is usually taken to be the point at which the particles can be resolved in an optical microscope.

Colloidal particles may be gaseous, liquid, or solid, and occur in various types of suspensions:

Sols - dispersions of small solid particles in a liquid.

Emulsions - colloidal systems in which the dispersed and continuous phases are both liquids.

Gels - colloids in which both dispersed and continuous phases have a three-dimensional network throughout the material.

Aerosols - colloidal dispersions of liquid or solid particles in a gas.

Foams - dispersions of gases in liquids or solids.

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.

colloid ion    →   koloidni ion

Colloid ions emerge when colloid particles adsorb certain type of ion from solution and thus become charged with the same charge. The charge can also originate form a chemical reaction of colloid particle’s surface. Colloid ions formed by absorption of silver chloride particle can be show as follows:

Adsorbed layer is monomolecular (one molecule thick) and which type of ion will be formed depends upon which ions are present in a greater number in the solution in. Because of this colloid particles are charged with the same charge, mutual repelling occurs, and the colloid solution becomes stable. Colloid charge can be determined by electrophoresis.

colloid mill    →   koloidni mlin

Colloid mills are machines used to grind aggregates into very fine particles or to apply very high shearing within a fluid to produce colloid suspensions or emulsions in which the particle sizes are less than 1 micrometer. One type of colloid mill is called a disc mill, in which a mixture of a solid and liquid (or two liquids) is passed between two discs a small distance apart, which rotate very rapidly relative to each other. Applications of colloid mills occur in food processing, in paint manufacture, and in the pharmaceutical industry.

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.

conditional electrode potential    →   uvjetni elektrodni potencijal

Conditional or formal electrode potential (E°’) is equal to electrode potential (E) when overall concentrations of oxidised and reduced form in all its forms in a solution are equal to one. Conditional electrode potential includes all effects made by reactions that do not take part in the electron exchange, but lead to change of ion power, changes of pH, hydrolysis, complexing, precipitating, etc.

At 298 K (25 °C) and by converting natural (Napierian) logarithms into decimal (common, or Briggian) logarithms, Nernst’s equation for electrode potential can be written as follows:

enthalpy growth    →   prirast entalpije

Enthalpy growth (ΔH) is that part of energy of system which can be translated into heat (Q) with a permanent pressure.