CHEMISTRY GLOSSARY

chemical equation equalization    →   izjednačavanje kemijske jednadžbe

Chemical equation equalization is determining values of stechiometric coefficients of reactants and products in a chemical equation in a way that the number of atoms of each element is equal before and after the reaction.

chemical kinetics    →   kemijska kinetika

Chemical kinetics is an area of chemistry that studies rates and mechanisms of chemical reactions.

battery    →   baterija

Battery a device that converts chemical energy to electrical energy. The process underlying the operation of a battery involves a chemical reaction in which electrons are transferred from one chemical species to another. This process is carried out in two half-reactions, one that involves the loss of electrons and one that involves their gain. The battery is an electrochemical cell divided in two half-cells, and reaction proceeds when these are connected together by an electrically conducting pathway. The passage of electrons from one half-cell to the other corresponds to an electric current. Each half-cell contains an electrode in contact with the reacting species. The electrode which passes electrons into the circuit when battery discharges is called anode and is negative terminal. The electrode which receives electrons is called cathode, and is the battery’s positive terminal. The electrical circuit is completed by an electrolyte, an electrically conducting substance placed between the two electrodes which carriers a flow of charge between them. In wet cells, the electrolyte is a liquid containing dissolved ions, whose motion generates an electrical current; in dry cells the electrolyte is basely solid, for example, a solid with mobile ions or porous solid saturated with an ionic solution.

blast furnace    →   visoka peć

Blast furnace is a furnace for smelting of iron from iron oxide ores (hematite, Fe₂O₃ or magnetite, Fe₃O₄). Coke, limestone and iron ore are poured in the top, which would normally burn only on the surface. The hot air blast to the furnace burns the coke and maintains the very high temperatures that are needed to reduce the ore to iron. The reaction between air and the fuel generates carbon monoxide. This gas reduces the iron(III) oxide in the ore to iron.

Because the furnace temperature is in the region of 1500 °C, the metal is produced in a molten state and this runs down to the base of the furnace.

The production of iron in a blast furnace is a continuous process. The furnace is heated constantly and is re-charged with raw materials from the top while it is being tapped from the bottom. Iron making in the furnace usually continues for about ten years before the furnace linings have to be renewed.

chemiluminescence    →   kemiluminiscencija

Chemiluminescence is energy release in form of electromagnetic radiation during a chemical reaction.

complete ionic equation    →   potpuna ionska jednadžba

Complete ionic equation is a balanced equation that describes a reaction occurring in a solution, in which all strong electrolytes are written as dissociated ions.

complex    →   kompleks

Complex or coordination compound is formed when metal ion (central ion) reacts with molecules or ions which have free electron pairs (ligand). Metal ion and ligand are bonded with a polar covalent bond in which both electrons are given by the ligand.

condensational polymerisation    →   kondenzacijska polimerizacija

Condensational polymerisation is a reaction of polymerisation in which monomers together create a polymer by losing small molecules like water.

Born-Haber cycle    →   Born-Haberov kružni proces

Born-Haber cycle is a cycle of reactions used for calculating the lattice energies of ionic crystalline solids. For a compound MX, the lattice energy is the enthalpy of the reaction

The standard enthalpy of formation of the ionic solid is the enthalpy of the reaction

The cycle involves equating this enthalpy (which can be measured) to the sum of the enthalpies of a number of steps proceeding from the elements to the ionic solid. The steps are:

1) Atomization of the metal

2) Atomization of the nonmetal

3) Ionisation of the metal

This is obtained from the ionisation potential.

4) Ionisation of the nonmetal

This is electron affinity.

5) Formation of the ionic solids

Equation of the enthalpies gives

from which ΔH_L can be found.

Butler-Volmer equation    →   Butler-Volmerova jednadžba

Butler-Volmer equation is an activation controlled reaction, the one for which the rate of reaction is controlled solely by the rate of the electrochemical charge transfer process, which is in turn an activation-controlled process. This gives rise to kinetics that are described by the Butler-Volmer equation:

where i_o is exchange current density, η is overpotential (η = E - E_o), n is number of electrons, α_A is anodic transfer coefficient, and α_C is cathodic transfer coefficient