CHEMISTRY GLOSSARY

gunpowder    →   barut

Gunpowder (black powder) is a low explosive composed of potassium nitrate, sulphur and charcoal. Typical proportions are 6:1:1.

harmonic motion    →   harmoničko gibanje

Harmonic motion is caused by restoring force, acting on a body that is displaced from its equilibrium position. This force tries to put the body back in equilibrium. Usual examples are the motion of a body attached to elastic spring (see: Hooke’s law) and the motion of mathematical pendulum. The body undergoes periodic motion around the equilibrium point.

heat    →   toplina

Heat is a form of energy associated with and proportional to molecular motion. It can be transferred from one body to another by radiation, conduction, or convection.

Heat of atomisation    →   toplina atomiziranja

Heat of atomisation or enthalpy of atomisation is the energy required to dissociate one mole of a given substance into atoms.

heat of combustion    →   toplina izgaranja

Heat of combustion or enthalpy of combustion is the heat evolved when a definite quantity of a substance is completely oxidised (burned).

dissociation    →   disocijacija

Dissociation is the process by which a chemical combination breaks up into simpler constituents as a result of either added energy (dissociated by heat), or the effect of a solvent on a dissolved polar compound (electrolytic dissociation). It may occur in the gaseous, solid, or liquid state, or in a solution.

An example of dissociation is the reversible reaction of hydrogen iodide at high temperatures

The term dissociation is also applied to ionisation reactions of acids and bases in water. For example

which is often regarded as a straightforward dissociation into ions

dissociation constant    →   konstanta disocijacije

Dissociation constant is a constant whose numerical value depends on the equilibrium between the undissociated and dissociated forms of a molecule. A higher value indicates greater dissociation.

The term dissociation is also applied to ionisation reactions of acids and bases in water. For example

which is often regarded as a straightforward dissociation into ions

The equilibrium constant of such a dissociation is called the acid dissociation constant or acidity constant, given by

The concentration of water [H₂O] can be taken as constant.

Similarly, for a base, the equilibrium

is also a dissociation; with the base dissociation constant or basicity constant, given by

K_a (K_b) is a measure of the strength of the acid (base).

heat of crystallization    →   toplina kristalizacije

Heat of crystallization or enthalpy of crystallization is the heat evolved or absorbed when one mole of given substance crystallises from a saturated solution of the same substance.

heat of formation    →   toplina nastajanja

Heat of formation or enthalpy of is formation the heat evolved or absorbed when one mole of a compound is formed in its standard state from its constituent elements.

heat of fusion    →   toplina taljenja

Heat of fusion or enthalpy of fusion is the heat required to convert a substance from the solid to the liquid state with no temperature change (also called latent heat of fusion or melting).