CHEMISTRY GLOSSARY

purification    →   pročišćavanje

Purification is the physical or chemical process of removing contaminants from a compound. The physical processes may include sublimation, distillation, filtration, crystallisation, or extraction. The chemical processes may involve formation of a derivative, purification of the derivative and recovery of the original material in a pure form of the derivative.

quantum chemistry    →   kvantna kemija

Quantum chemistry is a theoretical branch of chemistry that concerns the application of quantum mechanics to chemical problems.

racemisation    →   racemizacija

Racemisation is a conversion, by heat or by chemical reaction, of an optically active compound into an optically inactive form which half of the optically active substance becomes its miror image (enantiomer).

reactant    →   reaktant

Reactants are initial materials in a chemical reaction.

reaction mechanism    →   reakcijski mehanizam

Reaction mechanism is a list of all elementary reactions that occur in the course of an overall chemical reaction.

reactivity    →   reaktivnost

Reactivity is the tendency of a compound to chemically react with other substances or itself, resulting in the release of energy.

reagent    →   reagens

Reagents are any substance used in a chemical reaction to detect, measure, examine, or produce other substances.

galvanic celll    →   galvanski članak

Galvanic cell (voltaic cell) is a simple device with which chemical energy is converted into electrical energy. Galvanic cells consist of two separate compartments called half cells containing electrolyte solutions and electrodes that can be connected in a circuit. Two dissimilar metals (e.g., copper and zinc) are immersed in an electrolyte. If the metals are connected by an external circuit, one metal is reduced (i.e., gains electrons) while the other metal is oxidized (i.e., loses electrons).

In the example above, copper is reduced and zinc is oxidized. The difference in the oxidation potentials of the two metals provides the electric power of the cell.

A voltaic cell can be diagrammed using some simple symbols. In the diagram the electrodes are on the outer side of the diagram and a vertical line (|) is used to separate the electrode from the electrolyte solution found in the compartment. A double vertical line (||) is used to separate the cell compartments and is symbolic of the salt bridge. Usually in a diagram the species oxidized is written to the left of the double slash. Here is an example of the Daniell cell:

The names refer to the 18th-century Italian scientists Alessandro Volta (1745-1827) and Luigi Galvani (1737-1798).

germanium    →   germanij

Germanium was discovered by Clemens Winkler (Germany) in 1886. The origin of the name comes from the Latin word Germania meaning Germany. It is greyish-white semi-metal. Unaffected by alkalis and most (except nitric) acids. Stable in air and water. Germanium is obtained from refining copper, zinc and lead. Widely used in semiconductors. It is a good semiconductor when combined with tiny amounts of phosphorus, arsenic, gallium and antimony.

reversible cell    →   povrativi članak

Reversible cell is an electrical cell the chemical action in which can be reversed by passing through it a current opposite in direction to that generated by the cell.