CHEMISTRY GLOSSARY

centrifuge    →   centrifuga

Centrifuge is a device in which solid or liquid particles of different densities are separated by rotating them in a tube in a horizontal circle. The dense particles tend to move along the length of the tube to a greater radius of rotation, displacing the lighter particles to the other end.

crystal    →   kristal

Crystal is a solid with a regular geometric shape, having a characteristic internal structure and enclosed by symmetrically arranged plane surfaces, intersecting at definite and characteristic angles. In crystals the particles (atoms, ions, or molecules) have a regular three-dimensional repeating arrangement in space. This is called the crystal structure. The crystal lattice is the arrangement of points in space at which the particles are positioned.

Dalton, John    →   Dalton, John

Dalton, John (1766-1844) British chemist and physicist. In 1801 he formulated his law of partial pressures (Dalton’s law), but he is best remembered for Dalton’s atomic theory, which he announced in 1803. Dalton also studied colour blindness (a condition, once called Daltonism, that he shared with his brother).

deuterium lamp    →   deuterijeva svjetiljka

Deuterium or hydrogen lamp is used as a source of continuous radiation in UV part of the spectrum.

change of state    →   promjena stanja

Change of state is a physical change which appears when a substance crosses from one state into another. This usually happens because of the change of energy of particles provoked by heating or cooling.

chemical equation    →   kemijska jednadžba

Chemical equation is a way of denoting a chemical reaction using the symbol for the participating particles (atoms, molecules, ions, etc.); for example,

The single arrow is used for an irreversible reaction; double arrows are used for reversible reactions. When reactions involve different phases, it is usual to put the phase in brackets after the symbol.

The numbers a, b, c, and d, showing the relative numbers of molecules reacting, are called the stoichiometric coefficients. The convention is that stoichiometric coefficients are positive for reactants and negative for products. If the sum of the coefficients is zero, the equation is balanced.

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.

diffusion current    →   difuzijska struja

Diffusion current (i_d) is a current which is limited by the speed of particle diffusion in an electrolyte solution.

digestion    →   digeriranje

Digestion or precipitate ageing happens when freshly formed precipitate are left, usually at a higher temperature, in a solution from which it is precipitated. It results in cleaner and bigger particles.

dissolved substance    →   otopljena tvar

Dissolved substance is a solid, liquid or gas matter dissolved in a solvent. Depending upon the particle size of dissolved substance, solutions differ in properties and can be divided into real solutions (diameter of particles is smaller than 1 nm), colloid solutions (diameter of particles is from 1 nm to 200 nm) and suspensions (diameter of particles is greater than 200 nm).