CHEMISTRY GLOSSARY

chemical potential    →   kemijski potencijal

For a mixture of substances, the chemical potential of constituent B (μ_B) is defined as the partial derivative of the Gibbs energy G with respect to the amount (number of moles) of B, with temperature, pressure, and amounts of all other constituents held constant.

Also called partial molar Gibbs energy. Components are in equilibrium if their chemical potentials are equal.

chemical compound    →   kemijski spoj

Some substance is a compound only if it can be decomposed into two or more different substances by means of a chemical reaction. If two or more substances react, thus creating a new substance, that new substance is called a chemical compound.

chemical element    →   kemijski element

Chemical element is a type of matter of which elementary matter is composed. Chemical element is composed of atoms with the same core charge.

chemical symbols    →   kemijski simboli

Chemical symbols are a derived way of showing elements in a formula or equation. Each symbol represents one atom and it usually consists of the first two letters of the Greek or Latin name of the element.

cell potential    →   potencijal članka

Cell potential (E) is difference between anode and cathode potential. If the cell potential is positive, then the reaction is spontaneous.

decomposition potential    →   potencijal razlaganja

Decomposition potential of some system is the smallest voltage which should be applied so that electrolysis occurs.

Donnan potential    →   Donnanov potencijal

Donnan potential is the electrical potential difference between two solutions separated by an ion-exchange membrane in the absence of any current flowing through the membrane

electrochemical potential    →   elektrokemijski potencijal

Electrochemical potential is a measure of a metal to form ions in a liquid.

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:

electrode potential    →   elektrodni potencijal

Electrode potential is defined as the potential of a cell consisting of the electrode in question acting as a cathode and the standard hydrogen electrode acting as an anode. Reduction always takes place at the cathode, and oxidation at the anode. According to the IUPAC convention, the term electrode potential is reserved exclusively to describe half-reactions written as reductions. The sign of the half-cell in question determines the sign of an electrode potential when it is coupled to a standard hydrogen electrode.

Electrode potential is defined by measuring the potential relative to a standard hydrogen half cell

The convention is to designate the cell so that the oxidised form is written first. For example

The e.m.f. of this cell is

By convention, at p(H₂) = 101325 Pa and a(H⁺) = 1.00, the potential of the standard hydrogen electrode is 0.000 V at all temperatures. As a consequence of this definition, any potential developed in a galvanic cell consisting of a standard hydrogen electrode and some other electrode is attributed entirely to the other electrode