CHEMISTRY GLOSSARY

coenzyme a    →   koenzim a

Coenzyme A (CoA) is an essential metabolic cofactor synthesized from cysteine, pantothenate (vitamin B5), and ATP. CoA plays important roles in many metabolic pathways, including the tricarboxylic acid (TCA) cycle, and the synthesis and oxidation of fatty acids. One of the main functions of CoA is the carrying and transfer of acyl groups. Acylated derivatives (acetyl-CoA) are critical intermediates in many metabolic reactions.

element    →   element

Element is a substance that cannot be decomposed into simpler substances. In an element, all the atoms have the same number of protons or electrons, although the number of neutrons my vary.

complexometry    →   kompleksometrija

Complexometry is a volumetric analytic method which is based on titration of metal ion solutions with a substance that, combined with metal ions yields complex compounds, e.g. EDTA. The stoichiometric ratio of EDTA-metal in complexometric analyses is always 1:1, whatever the valency of the metal

conditional electrode potential    →   uvjetni elektrodni potencijal

Conditional or formal electrode potential (E°’) is equal to electrode potential (E) when overall concentrations of oxidised and reduced form in all its forms in a solution are equal to one. Conditional electrode potential includes all effects made by reactions that do not take part in the electron exchange, but lead to change of ion power, changes of pH, hydrolysis, complexing, precipitating, etc.

At 298 K (25 °C) and by converting natural (Napierian) logarithms into decimal (common, or Briggian) logarithms, Nernst’s equation for electrode potential can be written as follows:

equivalent weight    →   ekvivalentna masa

Equivalent weight of a substance participating in a neutralization reaction is that mass of substance (molecule, ion, or paired ion) that either reacts with or supplies 1 mol of hydrogen ions in that reaction.

Equivalent weight of a substance participating in an oxidation/reduction reaction is that weight which directly or indirectly produces or consumes 1 mol of electrons.

fermentation    →   fermentacija

Fermentation is a class of biochemical reactions that break down complex organic molecules (such as carbohydrates) into simpler materials (such as ethanol, carbon dioxide, and water). Fermentation reactions are catalyzed by enzymes.

formula    →   formula

See Chemical compound formula

Contat-Gockel’s valve    →   Contat-Gockelov ventil

Contat-Göckel’s valve is used for maintenance of inert atmosphere in a flask. The valve is filled with a saturated solution of sodium bicarbonate (NaHCO₃) so that the end of the tube is covered. Solution inside the valve keeps the flask contents away from the oxygen influence from air. If low pressure is created inside the flask (when the flask is cooled), the solution will penetrate inside it from funnel and in a reaction with acid CO₂ is generated which fills up the flask.

Solution from the funnel will keep penetrating until CO₂ pressure in the flask is equalised with the outer pressure.

copolymer    →   kopolimer

Copolymers are also known as heteropolymers. They are made from two (or more) different monomers, which usually undergo a condensation reaction with the elimination of a simple molecule, such as ammonia or water. A typical example is the condensation of 1,6-diaminohexane (hexamethylenediamine) with hexanedioic acid (adipic acid) to form nylon 6,6.

The properties of a polymeric plastic can most easily be modified if it is a copolymer of two or more different monomers, e.g. acrylonitrile-butadiene-styrene copolymer (ABS). Varying the proportions of the component monomers can preselect its properties.

corrosion    →   korozija

Corrosion is a harmful and undesirable construction material consumption by the chemical activity of its surroundings. Corrosion concept refers to metal and nonmetal construction materials, but it is usually used for metals, Corrosion of metal, according to the mechanism process, is divided into chemical (corrosion in nonelectrolytes) and electrochemical (corrosion in electrolytes).

Chemical corrosion appears by direct action of molecule of some element or compound on metal, thus directly creating corrosion products.

Electrochemical corrosion of metals occurs in electrolytes, so reduction of metal atom into free cation appears which by secondary processes gives molecules of compound which are considered a corrosion product.