CHEMISTRY GLOSSARY

glycosyl group    →   glikozidna skupina

The structure obtained by removing the hydroxy group from the hemiacetal function of a monosaccharide.

gravimetrical factor    →   gravimetrijski faktor

Gravimetrical factor is stechiometric proportion between molar mass of analyte and molar mass of precipitate in gravimetry.

gravitational constant    →   gravitacijska konstanta

Gravitational constant (G) is the universal constant in the equation for the gravitational force between two particles

where r is the distance between the particles and m₁ and m₂ are their masses.

electrochemical cell    →   elektrokemijski članak

Electrochemical cell is a device that converts chemical energy into electrical energy or vice versa when a chemical reaction is occurring in the cell. It consist of two electronically conducting phases (e.g., solid or liquid metals, semiconductors, etc) connected by an ionically conducting phase (e.g. aqueous or non-aqueous solution, molten salt, ionically conducting solid). As an electric current passes, it must change from electronic current to ionic current and back to electronic current. These changes of conduction mode are always accompanied by oxidation/reduction reactions.

An essential feature of the electrochemical cell is that the simultaneously occurring oxidation-reduction reactions are spatially separated. E.g., in a spontaneous chemical reaction during the oxidation of hydrogen by oxygen to water, electrons are passed directly from the hydrogen to the oxygen.

In contrast, in the spontaneous electrochemical reaction in a galvanic cell the hydrogen is oxidised at the anode by transferring electrons to the anode and the oxygen is reduced at the cathode by accepting electrons from the cathode. The ions produced in the electrode reactions, in this case positive hydrogen ions and the negative hydroxyl (OH^-) ions, will recombine in the solution to form the final product of the reaction: water. During this process the electrons are conducted from the anode to the cathode through an outside electric circuit where the electric current can drive a motor, light a light bulb, etc. The reaction can also be reversed: water can be decomposed into hydrogen and oxygen by the application of electrical power in an electrolytic cell.

electrochemical series    →   elektrokemijski niz

Electrochemical series is a series of chemical elements arranged in order of their standard electrode potentials. The hydrogen electrode

is taken as having zero electrode potential. An electrode potential is, by definition, a reduction potential.

Elements that have a greater tendency than hydrogen to lose electrons to their solution are taken as electropositive; those that gain electrons from their solution are below hydrogen in the series and are called electronegative.

The series shows the order in which metals replace one another from their salts; electropositive metals will replace hydrogen from acids.

electrode of the first kind    →   elektroda prvog reda

Electrode of the first kind is a simple metal electrode immersed in a solution containing its own ion (e.g., silver immersed in a silver nitrate solution). The equilibrium potential of this electrode is a function of the concentration (more correctly of activity) of the cation of the electrode metal in the solution (see Nernst’s electrode potential equation).

gray    →   grej

Gray (Gy) is the SI derived unit of absorbed dose of radiation. The gray is the absorbed dose when the energy per unit mass imparted to matter by ionising radiation is one joule per kilogram (Gy = J/kg). The unit was named after the British scientist Louis Harold Gray (1905-1965).

Grignard reagent    →   Grignardov reagens

Grignard reagents are organomagnesium halides, RMgX, having a carbon- magnesium bond (or their equilibrium mixtures in solution with R₂Mg + MgX₂).

Haber, Fritz    →   Haber, Fritz

Fritz Haber (1868-1934) is German physical chemist, winner of the Nobel Prize for Chemistry (1918) for his development of a method of synthesizing ammonia. With Carl Bosch, he invented a process for the large-scale production of ammonia for use in nitrogen fertilizer.

electrode of the second kind    →   elektroda drugog reda

Electrodes of the second kind are metal electrodes assembly with the equilibrium potential being a function of the concentration of an anion in the solution. Typical examples are the silver/silver-chloride electrode and the calomel electrode. The potential of the metal is controlled by the concentration of its cation in the solution, but this, in turn, is controlled by the anion concentration in the solution through the solubility product of the slightly soluble metal salt. Contrast with electrode of the first kind and electrode of the third kind.