CHEMISTRY GLOSSARY

catalyst    →   katalizator

Catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change. Catalysts that have the same phase as the reactants are homogenous catalysts (e.g. enzymes in biochemical reactions). Those that have a different phase are heterogeneous catalyst (e.g. metals or oxides used in gas reactions).

The catalyst provides an alternative pathway by which the reaction can proceed, in which the activation energy is lower. In thus increases the rate at which the reaction comes to an equilibrium, although it does not alter the position of the equilibrium.

accelerator    →   akcelerator

Accelerator is a device (machine) used for acceleration of charged particles (protons, deuterons, α-particles). Particles are accelerated under the influence of an electric field and with the help of a magnetic field are kept inside a certain space. When the particles reach enough acceleration (that is sufficient energy), they are directed on a target we wish to bomb. Best known types cyclotron, synchrotron, betatron.

Accelerator is a substance that increases the rate of chemical reaction, i.e. a catalyst.

activator    →   aktivator

Activator is a substance that increases the activity of a catalyst; for example, a substance that - by binding to an allosteric site on an enzyme - enables the active site of the enzyme to bind to the substrate.

autocatalysis    →   autokataliza

Autocatalysis is a reaction in which its product can act as a catalyst. Oxalate oxidation with permanganate in an acid solution is a slow reaction

Mn²⁺-ions catalyse this reaction. When enough Mn²⁺-ions are created, the reaction occurs instantly.

catalytic cracking    →   katalitčko krekiranje

Catalytic cracking is a petroleum refining process in which heavy-molecular weight hydrocarbons are broken up into light hydrocarbon molecules by the application of heat and pressure in the presence of a catalyst.

catalytic hydrogenation    →   katalitičko hidrogeniranje

Catalytic hydrogenation is the infusing of unsaturated or impure hydrocarbons with hydrogen gas at controlled temperatures and pressures and in the presence of a catalyst for the purpose of obtaining saturated hydrocarbons and/or removing various impurities such as sulphur and nitrogen.

formaldehyde    →   formaldehid

Formaldehyde (methanal) is a colourless gas, HCHO; r.d. 0.815 (at -20 °C); m.p. -92 °C; b.p. -21 °C. It is the simplest aldehyde, made by the catalytic oxidation of methanol (500 °C; silver catalyst) by air. It forms two polymers: methanal trimer and polymethanal.

promoter    →   promotor

Promoter is any component added to a catalyst to increase activity or selectivity. Examples are tin added to platinum reforming catalysts to improve selectivity to coke formation and chloride added to isomerization catalysts to increase activity.

contact procedure    →   kontaktni postupak

Contact procedure is an industrial procedure used for the production of sulphuric acid, where a dry and clean sulphur dioxide and air go over a catalyst made of vanadium pentoxide at 450 °C by which sulphur trioxide is gained, then we add concentrated sulphuric acid by which we obtain smoking sulphuric acid which is now diluted to sulphuric acid.

enzyme    →   enzim

Enzyme is a protein that acts as a catalyst in biochemical reactions. Each enzyme is specific to a particular reaction or a group of similar reactions. Many require the association of certain nonprotein cofactors in order to function. The molecule undergoing a reaction (the substrate) binds to a specific active site on the enzyme molecule to form a short-lived intermediate: this greatly increases (by a factor of up to 10²⁰) the rate at which the reaction proceeds to form the product.