CHEMISTRY GLOSSARY

gold    →   zlato

Gold has been known since ancient times. The origin of the name comes from the Latin word aurum meaning gold. It is soft, malleable, bright yellow metal. Unaffected by air, water, alkalis and most acids. Gold is found in veins in the crust, with copper ore and native. Used in electronics, jewellery and coins. It is a good reflector of infrared radiation, so a thin film of gold is applied to the glass of skyscrapers to reduce internal heating from sunlight.

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:

arsenic    →   arsen

Arsenic was discovered by Albertus Magnus (Germany) in 1250. The origin of the name comes from the Greek word arsenikon meaning yellow orpiment. It is steel-grey, brittle semi-metal. Resists water, acids and alkalis. Tarnishes in air, burns in oxygen. Highly toxic by inhalation or ingestion. Arsenic is found in mispickel (arsenopyrite). Many of its compounds are deadly poison and used as weed killer and rat poison. Used in semiconductors. Some compounds, called arsenides, are used in the manufacture of paints, wallpapers and ceramics.

beer    →   pivo

Beer is a barley and hop flavored alcoholic beverage. Beer is made by fermenting a mixture of water, barley, hops and yeast with addition of special yeast. It contains from 2 % to 5 % of alcohol. Beer is light golden yellow to reddish to almost black.

carat    →   karat

Carat (ct.) is a metric unit of mass for the weighing of precious metals, precious stone and gems (e.g. diamond, ruby, sapphire).

Carat (ct, Kt) corresponds to the mass fraction of gold in precious alloys used in jewellery.

1 ct = 0.4167 %

24 ct = 100 %

24 carat gold is pure gold, 18 carat is 75 % gold and 25 % of some other metal such as silver or copper.

chromium    →   krom

Chromium was discovered by Louis-Nicholas Vauquelin (France) in 1797. The origin of the name comes from the Greek word chroma meaning colour. It is very hard, crystalline, steel-grey metal. The pure metal has a blue-white colour. It is hard, brittle and corrosion-resistant at normal temperatures. Hexavalent compounds toxic by skin contact. The most important chromium mineral is chromite [Fe,Mg(CrO₄)]. Produced commercially by heating its ore in the presence of silicon or aluminium. Used to make stainless steel. It gives the colour to rubies and emeralds. Iron-nickel-chromium alloys in various percentages yield an incredible variety of the most important metals in modern technology.

cyanide process    →   cijanidni postupak

Cyanide process is a method for separating a metal from an ore. Crushed ore is treated with cyanide ion to produce a soluble metal cyanide complex. The complex is washed out of the ore and reduced to metallic form using an active metal (usually zinc).

royal water    →   carska voda

See Aqua regia

size of the nucleus    →   veličina jezgre

Size of the nucleus was measured by Lord Rutherford using the scattering patterns of alpha particles passing through a gold foil. It is 10^-15 m.

invert sugar    →   invertni šećer

Invert sugar is a mixture of equal parts of glucose and fructose resulting from the hydrolysis of sucrose (saccharose). The name stemming from the fact that it rotates of plane polarized light in the opposite direction of sucrose. Sucrose is dextrorotatory - it rotates polarized light clockwise ([α]_D = +66.5°). Invert sugar rotates the plane of the polarized light counterclockwise ([α]_D = -22°) due to the strongly levorotatory nature of fructose ([α]_D = -92°).

Homemade artificial honey (invert sugar syrup): Dissolve two parts of household sugar (1 kg) with stirring in one part of water (0.5 kg) in a saucepan over low heat. Add 1 g of citric acid or the juice of one lemon to the mixture. Bring the ingredients to a slow boil. It can take anywhere between 15 minutes to 1 hour. The end result is sticky, golden syrup. Let it sit at room temperature until it is cool.