CHEMISTRY GLOSSARY

isochore    →   izohora

Isochore is a line or surface of constant volume on a graphic representation of a physical system.

latent heat    →   latentna toplina

Latent heat (L) is the quantity of heat absorbed or released when a substance changes its physical phase at constant temperature (e.g. from solid to liquid at the melting point or from liquid to gas at the boiling point).

law of conservation of energy    →   zakon o očuvanju energije

Law of conservation of energy: In an isolated system energy can be transferred from one form to another but the total energy of the system remains constant.

photon    →   foton

Photon is an elementary particle of zero mass and spin 1/2. The photon is involved in electromagnetic interactions and is the quantum of electromagnetic radiation. The photon may also be regarded as a unit of energy equal to

where h is Planck constant and ν is the frequency of the radiation.

pK    →   pK

pK is the negative logarithm (base 10) of an equilibrium constant K.

quantum    →   kvant

Quantum is the smallest quantity of energy that can be emitted (or absorbed) in the form of electromagnetic radiation. Energy of a quantum (E) is equal to

where h is Planck constant and ν is the frequency of radiation.

enthalpy    →   entalpija

Enthalpy (H) is a thermodynamic property of a system defined by

where U is the internal energy of the system, p its pressure, and V its volume. J.W. Gibbs put the concept of an ensemble forward in 1902. In a chemical reaction carried out in the atmosphere the pressure remains constant and the enthalpy of reaction (ΔH), is equal to

For an exothermic reaction ΔH is taken to be negative.

Faraday’s laws of electrolysis    →   Faradayevi zakoni elektrolize

Faraday’s laws of electrolysis are two laws found by British chemist and physicist Michael Faraday (1791-1867) in his experiments on electrolysis:

1. The quantity of matter extracted on the electrode is proportional to the quantity of charge (Q = I·t) which has flown in electrolysis time.

where z = number of electrons changed in reaction and F = Faraday’s constant which equals 96 487 C mol^-1.

2. The masses of the elements liberated by the same quantity of electricity are directly proportional to their chemical equivalents.

96 487 C will discharge 1 mol Ag and 1/2 mol Cu. The relevant half reactions are:

filtration    →   filtriranje

Filtration is a procedure in which liquids are separated from the precipitate by passing a suspension through the filter. The precipitate remains on the filter and through it the filtrate passes. Gaseous heterogeneous mixtures can also be filtrated.

salt fog chambers    →   slana komora

Salt fog chambers are designed for corrosive atmosphere testing. The samples being tested are inserted into the chamber and then the salt-containing solution is sprayed as a very fine fog mist over the samples. The temperature within the chamber is maintained constant (usually 35 °C). These test chambers are constructed of non-corrosive materials.