CHEMISTRY GLOSSARY

unequal-arm balance    →   vaga s različitim krakovima

The lever principle on which these scales are constructed is based on the law of physics that at equilibrium the force applied at one end of the lever multiplied by the length of the arm (distance from the fulcrum to the point where the force is applied) must be equal to the product of the force acting at the opposite end of the lever and the length of the other arm.

The unequal-arm balance is preferred for work when large amounts are to be weighed.

acceptor    →   akceptor

Acceptor is a compound, molecule or ion, to which electrons are donated in the formation of a coordinate bond

acetal    →   acetal

Acetals are organic compounds having the structure R₂C(OR’)₂ (R’ ≠ H). They are organic compounds formed by addition of alcohol molecules to aldehyde or ketone molecules. Originally, the term was confined to derivatives of aldehydes (one R = H), but it now applies equally to derivatives of ketones (neither R = H ). Mixed acetals have different R’ groups. The formation of acetals is reversible; acetals can be hydrolysed back to aldehydes (ketone) in acidic solutions.

Acetal, 1,1-diethoxyethane (CH₃CH(OC₂H₅)₂), is an organic compound, pleasant smelling, formed by addition of ethyl alcohol to ethanal (acetaldehyde). It is used as a solvent and in synthetic organic chemistry.

acetate    →   acetat

1. Acetate is an ion formed by removing the acidic hydrogen from acetic acid, HC₂H₃O₂.

2. Acetate is a compound derived by replacing the acidic hydrogen in acetic acid.

3. Acetate is a fibre made of cellulose acetate.

Acheson process    →   Achesonov proces

Acheson process is an industrial process to synthesize graphite and silicon carbide (carborundum), named after its inventor the American chemist Edward Goodrich Acheson (1856-1931). In this process, a solid-state reaction between pure silica sand (SiO₂) and petroleum coke (C) at very high temperature (more than 2500 °C) leads to the formation of silicon carbide under the general reaction:

While studying the effects of high temperature on carborundum, Acheson had found that silicon vaporizes at about 4150 °C, leaving behind graphitic carbon.

acid salt    →   kisela sol

Acid salt is a compound formed by replacing hydrogen in an acid with a metal (or a radical that acts like a metal).

acrylic acid    →   akrilna kiselina

Acrylic acid (propenoic acid) is a colourless liquid, smelling like acetic acid. It can be formed by acrolein oxidation. It readily polymerizes and is used in the manufacture of acrylic resins, transparent plastic materials (organic glass).

activated complex    →   aktivirani kompleks

Activated complex is an intermediate structure formed in the conversion of reactants to products. The activated complex is the structure at the maximum energy point along the reaction path; the activation energy is the difference between the energies of the activated complex and the reactants.

alabaster    →   alabaster

Alabaster is a monoclinic mineral form of hydrated calcium sulphate. It is a pure fine-grained translucent form of gypsum. CaSO₄·2H₂O.

aldehydes    →   aldehidi

Aldehydes are a broad class of organic compounds having the generic formula RCHO, and characterized by an unsaturated carbonyl group (C=O). They are formed from alcohols by either dehydrogenation or oxidation. Their chemical derivation is indicated by the name al(cohol) + dehyd(rogenation). An example of these distinct aromatic compounds is formaldehyde.