CHEMISTRY GLOSSARY

reversible cell    →   povrativi članak

Reversible cell is an electrical cell the chemical action in which can be reversed by passing through it a current opposite in direction to that generated by the cell.

newton    →   njutn

Newton (N) is the SI unit of force, being the force required to give a mass of one kilogram an acceleration of 1 m s^-2 (N = kg m s^-2). It was named after the British scientist Sir Isaac Newton (1642-1727).

rheology    →   reologija

Rheology is the study of the deformation and flow of materials. Has important bearing on the behaviour of viscous liquids in plastic molding.

ricin    →   ricin

Ricin is a toxin derived from the castor bean. It can be spread in aerosol or liquid form. It causes blood poisoning and leads to the collapse of the circulatory system and a slow death.

sample    →   uzorak

In chemical analysis total amount of matter is not analysed, but only a smaller part of it. This small part is called analysis sample and it must represent the whole amount of the matter that is being analysed.

sand    →   pijesak

Sand is loose particles of hard, broken rock or minerals, with a diameter of between 0.02 mm and 2 mm. Sand is the most common form of silica used in making glass.

saponification    →   saponifikacija

Saponification is a proces of hydrolysis of esters using hot sodium hydroxide solution to produce the salt of a carboxylic acid. Saponification usually refers to the hydrolysis of esters of fatty acids to manufacture soaps.

Newton’s gravitational law    →   Newtonov zakon gravitacije

Every object in the universe attracts every other object with a force (gravitational force F_G) directed along the line through centres of the two objects that is proportional to the product of their masses and inversely proportional to the square of the distance between them.

m₁ and m₂ are masses of the two objects and r is the distance between them. G is universal constant of gravitation, which equals 6.67•10^-26 N m² kg^-2. Strictly speaking, this law applies only to objects that can be considered pointlike object. Otherwise, the force has to be found by integrating the forces between various mass elements.

It is more properly to express Newton’s gravitational law by vector equation:

in which r₁ and r₂ are position vectors of masses m₁ and m₂.

Gravitational forces act on distance. Newton’s gravitational law is derived from Kepler’s law for planetary motion, using a physical assumption considering Sun as the centre and the source of gravitational force.

Additionally, every object moves in the direction of the force acting on it, with acceleration that is inversely proportional to the mass of object. For bodies on the surface of Earth, the distance r in gravitational law formula is practically equal to the Earth radius, R_E. If the mass of the body on Earth surface is m and the mass of earth is M_E, the gravitational force acting on that body can be expressed as:

where g is gravitational acceleration which is, although dependent on geographical latitude, usually considered as constant equal to 9.81 m s^-2.

seaborgium    →   seaborgij

Seaborgium was discovered by workers at the Nuclear Institute at Dubna (USSR) and by workers at the University of California, Berkeley (USA) in 1974. Named in honour of Glenn T. Seaborg, American nuclear chemist and Nobel prize winner. It is synthetic radioactive metal. Seaborgium was made by bombarding californium-249 with oxygen-18.

nickel    →   nikal

Nickel was discovered by Axel Fredrik Cronstedt (Sweden) in 1751. The origin of the name comes from the German word kupfernickel meaning Devil’s copper or St Nicholas’s (Old Nick’s) copper. It is hard, malleable, silvery-white metal. Soluble in acids, resist alkalis. It can be polished to a lustrous finish. Resists corrosion in air under normal conditions. Nickel is chiefly found in pentlandite [(Ni,Fe)₉S₈] ore. The metal is produced by heating the ore in a blast furnace which replaces the sulfur with oxygen. The oxides are then treated with an acid that reacts with the iron not the nickel. Used in electroplating and metal alloys because of its resistance to corrosion. Also in nickel-cadmium batteries, as a catalyst and for coins.