CHEMISTRY GLOSSARY

Knudsen’s pipette    →   Knudsenova pipeta

Kudsen's automatic pipette, developed by the Danish physicist Martin Knudsen (1871-1949), allows quick and accurate transfer of a constant volume of liquid (sea water), usually around 15 mL. On the top of pipette is a double sided C vent that can establish flow between the body of the pipette and one of the branches (A or B), or isolate the body of the pipette from both of the branches. Sucking through the B branch the pipette is filled with liquid, it is closed with a twist of the C valve and the liquid is released by rotating the valve towards the A branch (so atmospheric air can enter the pipette). Emptying the pipette takes around 30 seconds. Before it's first use, the pipette must be calibrated with distilled water.

Kohlrausch’s law    →   Kohlrauschov zakon

Kohlrausch’s law states that the equivalent conductivity of an electrolyte at infinite dilution is equal to the sum of the conductances of the anions and cations. If a salt is dissolved in water, the conductivity of the solution is the sum of the conductances of the anions and cations. The law, which depends on the independent migration of ions, was deduced experimentally by the German chemist Friedrich Kohlrausch (1840-1910).

lanthanum    →   lantan

Lanthanum was discovered by Carl Gustaf Mosander (Sweden) in 1839. The origin of the name comes from the Greek word lanthanein meaning to lie hidden. It is soft, silvery-white, malleable, ductile metal. Readily tarnishes in air. Reaction with water releases hydrogen gas. Metal ignites and burns readily. Reacts with oxidants. Lanthanum is found with rare earths in monazite and bastnasite. Monazite sand typical contains 25 % lanthanum. It is used in the electrodes of high-intensity, carbon-arc lights. Because it gives glass refractive properties, it is used in expensive camera lenses.

latex    →   lateks

Latex, also known as rubber or natural latex, is a milky fluid derived from the rubber tree. The latex is a colloid of caoutchouc (25-35%) dispersed in water (60-75%), which forms rubber by coagulation. The term is also applied to artificial emulsions of natural or artificial rubber, or of certain synthetic resins (such as polyvinyl acetate or polyvinyl chloride). It is used in a wide variety of consumer products, including rubber gloves, tubing, condoms, rubber bands, etc.

lead    →   olovo

Lead has been known since ancient times. The origin of the name comes from the Latin word plumbum meaning liquid silver. It is very soft, highly malleable and ductile, blue-white shiny metal. Tarnishes in moist air; stable in oxygen and water. Dissolves in nitric acid. Compounds toxic by inhalation or ingestion. Danger of cumulative effects. Lead is found most often in ores called galena or lead sulfide (PbS). Used in solder, shielding against radiation and in batteries.

Liebig condenser    →   Liebigovo hladilo

Liebig condenser is used for condensing of vapours that pass trough the centre tube. It is cooled with water that passes in the outer tube (shell around the centre tube) in the opposite direction than the one of hot vapour. Though named after the German chemist Justus von Liebig (1803-1873), he cannot be given credit for having invented it because it had already been in use for some time before him.

lime    →   živo vapno

Lime (or quicklime) is the common name for calcium oxide (CaO). It is manufactured from limestone, CaCO₃, by heating it to a high temperature (about 1 000 °C). At this temperature carbon dioxide, CO₂, is released from the limestone creating calcium oxide, CaO.

A further process involves adding water in a process known as hydrating, which produces hydrated, or slaked lime [Ca(OH)₂].

limestone    →   vapnenac

Limestone is a sedimentary rock composed primarily of calcium carbonate in the form of the mineral calcite.. Some 10 % to 15 % of all sedimentary rocks are limestones. Limestone is usually organic, but it may also be inorganic. Calcium carbonate may have been directly precipitated from the sea-water or by the lithification of coral reefs, marine organism shells, or marine organism skeletons.

lithium    →   litij

Lithium was discovered by Johan August Arfvedson (Sweden) in 1817. The origin of the name comes from the Greek word lithos meaning stone, apparently because it was discovered from a mineral source whereas the other two elements, sodium and potassium, were discovered from plant sources. It is soft silvery-white metal. Lightest of metals. Reacts slowly with water and oxygen. Flammable. Can ignite in air. Reacts with water to give off a flammable gas. Lithium is obtained by passing electric charge through melted lithium chloride and from the silicate mineral called spodumene [LiAl(Si₂O₆)]. Used in batteries. Also for certain kinds of glass and ceramics. Some is used in lubricants.

magnesium    →   magnezij

Magnesium was discovered by Sir Humphry Davy (England) in 1808. The origin of the name comes from the Greek word Magnesia, a district of Thessaly. It is lightweight, malleable, silvery-white metal. Burns in air with a brilliant white flame and reacts with water as temperature elevates. Can ignite in air. React violently with oxidants. Magnesium is found in large deposits in the form of magnesite, dolomite and other minerals. It is usually obtained by electrolysis of melted magnesium chloride (MgCl₂) derived from brines, wells and sea water. Used in alloys to make airplanes, missiles and other uses for light metals. Have structural properties similar to aluminium.