CHEMISTRY GLOSSARY

aqua regia    →   zlatotopka

Aqua regia is a mixture of one volume part of nitric acid (HNO₃) and three volume parts of hydrochloric acid (HCl). Dissolving of gold in aqua regia is described by the following equation:

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.

chlorine    →   klor

Chlorine was discovered by Carl William Scheele (Sweden) in 1774. The origin of the name comes from the Greek word chloros meaning pale green. It is greenish-yellow, disagreeable gas with irritating odour. Gas is toxic and severe irritant by contact or inhalation. Never found in free form in nature. Commercial quantities of chlorine are produced by electrolysis of aqueous sodium chloride (NaCl) from seawater or brine from salt mines. Used in water purification, bleaches, acids and many, many other compounds such as chlorofluorocarbons (CFC).

dolomite    →   dolomit

Dolomite is a carbonate mineral consisting of a mixed calcium-magnesium carbonate, CaCO₃·MgCO₃, crystallising in the rhombohedral system. It is usually white or colourless. The term is also used to denote a rock with a high ratio of magnesium to calcium carbonate.

fire-damp    →   plin praskavac

Fire-damp is a mixture of two volume parts of hydrogen and one volume part of oxygen which, if set on fire, strongly explodes, the flame giving of a very high temperature (2 000 °C).

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.

concentration    →   koncentracija

1. Group of four quantities characterizing the composition of a mixture with respect to the volume of the mixture (mass, amount, volume and number concentration).

2. Short form for amount (of substance) concentration (substance concentration in clinical chemistry).

electronegativity    →   elektronegativnost

Electronegativity is a parameter originally introduced by L. Pauling which describes, on a relative basis, the power of an atom to attract electrons. For example, in hydrogen chloride, the chlorine atom is more electronegative than the hydrogen and the molecule is polar, with a negative charge on the chlorine atom.

There are various ways of assigning values for the electronegativity of an element. Pauling electronegativities are based on bond dissociation energies using a scale in which fluorine, the most electronegative element, has the value 4 and francium, the lowest electronegative element, has the value 0.7.

heavy water    →   teška voda

Water molecules are composed of two hydrogen atoms and one oxygen atom (H₂O). If the hydrogen atoms of a water molecule are replaced by deuterium atoms, the result is heavy water (D₂O). Deuterium differs from hydrogen by having one neutron in the nucleus of the atom. There is approx. one part in 5000 D₂O in normal water and it can be concentrated by electrolysis. Heavy water has a higher boiling point (101.4 °C) and melts at 3.6 °C. Heavy water is 20/18=1.11 times heavier than ordinary water.

LPG    →   LPG

LPG (Liquid Petroleum Gas) is a mixture of short hydrocarbons with most of the volume being propane and butane. LPG is considered an alternative fuel that burns cleaner than petrol.