CHEMISTRY GLOSSARY

hydrosphere    →   hidrosfera

Hydrosphere (from the Greek for water sphere) is a discontinuous layer of water on, under, and over the Earth's surface. It includes all liquid and frozen surface waters, groundwater held in soil and rock, and atmospheric water vapour. Water continuously circulates between these reservoirs in what is called the hydrologic cycle, which is driven by energy from the Sun.

sublimation    →   sublimacija

Sublimation is the conversion of a substance from its solid form directly to its gaseous form without the intervening liquid form. Dry ice (frozen carbon dioxide) sublimates at normal room temperature.

supersaturated solution    →   prezasićena otopina

Solution is supersaturated when it contains greater quantity of dissolved substance in itself than it corresponds to solubility of that substance at that temperature. It is said to be in an unstable state, and by shaking the vessel containing that such a solution separation of salt surplus can occur.

indicator    →   indikator

Indicator is a substance used to show the presence of a chemical substance or ion by its colour. Acid-base indicators are compounds, such as phenolphtaleine and methyl orange, which change colour reversibly, depending on whether the solution is acidic or basic. Oxidation-reduction indicators are substances that show a reversible colour change between oxidised and reduced forms.

indium    →   indij

Indium was discovered by Ferdinand Reich and Hieronymus Theodor Richter (Germany) in 1863. Named after the indicum (colour indigo), the colour it shows in a spectroscope. It is rare, very soft, silver-white metal. Stable in air and water. Dissolves in acids. Metal can ignite and burn. Indium is found in certain zinc ores. Used to coat high speed bearings and as an alloy that lowers the melting point of other metals. Relatively small amounts are used in dental items and in electronic semiconductors.

Joule-Thomson coefficient    →   Joule-Thompsonov koeficijent

Joule-Thomson coefficient (μ) is a parameter which describes the temperature change when a gas expands adiabatically through a nozzle from a high pressure to a low pressure region. It is defined by

where H is enthalpy.

universal indicator    →   univerzalni indikator

Universal indicator is an indicator which undergoes several colour changes over a wide range of pH. The colour is used to indicate pH directly. Universal indicators are usually mixtures of several indicators.

vapour    →   para

Vapour is the gaseous state of some matter which can be converted into liquid when exposed to pressure.

volume    →   volumen

Volume is a space taken by a certain mass of some matter. SI unit for volume is a cubic meter (m³). Changes of temperature or pressure can change volume.

yeast    →   kvasac

Yeasts are a group of unicellular fungi which exist almost everywhere in nature. There are about 1500 species currently known to science. Yeast contains an enzyme called cimase which catalyses change of glucose in ethanol in the process of alcoholic fermentation.