CHEMISTRY GLOSSARY

beryllium    →   berilij

Beryllium was discovered by Friedrich Wöhler (Germany) and independently by A. B. Bussy (France) in 1828. The origin of the name comes from the Greek word beryllos meaning mineral beryl; also called glucinium from the Greek word glykys meaning sweet. It is steel-grey metal. It resists attack by concentrated nitric acid, has excellent thermal conductivity and is nonmagnetic. At ordinary temperatures, it resists oxidation in air. Beryllium and its salts are toxic and should be handled with the greatest of care. Beryllium is found mostly in minerals like beryl [AlBe₃(Si₆O₁₈)] and chrysoberyl (Al₂BeO₄). Pure beryllium is obtained by chemically reducing beryl mineral. Also by electrolysis of beryllium chloride. Its ability to absorb large amounts of heat makes it useful in spacecraft, missiles, aircraft, etc. Emeralds are beryl crystals with chromium traces giving them their green colour.

calomel electrode    →   kalomel elektroda

Calomel electrode is a type of half cell in which the electrode is mercury coated with calomel (Hg₂Cl₂) and the electrolyte is a solution of potassium chloride and saturated calomel. In the calomel half cell the overall reaction is

Table: Dependence of potential of calomel electrode upon temperature and concentration of KCl according to standard hydrogen electrode

chemical balance    →   kemijska ravnoteža

Chemical balance is a degree of reversible reaction in a closed system, when the forward and backward reaction happen at same rates and their effects annul each other, while the concentration of reactants and products stays the same.

coagulation    →   koaguliranje

Coagulation is a process of colloid particles merging into bigger ones. By removing the charge form a colloid ion, by increasing the temperature or by increasing electrolyte concentration, colloid particles will gather into bigger groups precipitate will emerge. Precipitate that is formed in this way (coagulate) is amorphic and considerably polluted with adsorbed pollutants.

colorimetry    →   kolorimetrija

Colorimetry is a quantitative chemical analysis by colour using a colorimeter.

dilute solution    →   razrijeđena otopina

Dilute solution contains a relatively low concentration of solute.

dilution    →   razrjeđivanje

Dilution is the action of diluting or reducing the strength or concentration of a liquid, usually by the addition of water.

Fick’s law    →   Fickov zakon

Fick’s law is the statement that the flux J of a diffusing substance is proportional to the concentration gradient, i.e.,

where D is called the diffusion coefficient.

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.

composition of ocean water    →   sastav oceanske vode

The proportions of the major constituents of ocean water are almost constant throughout the world. Salinity (total salt content) and the concentrations of individual chemical constituents in sea wateris given the units psu (practical salinity units). For most purposes one can assume that the new unit, psu, and the older unit, ‰, are synonymous.

The average composition of the ocean water is as shown on the following table.