CHEMISTRY GLOSSARY

foam    →   pjena

Foams are dispersions of gases in liquids or solids. The gas globule may be of any size, from colloidal to macroscopic, as in soap bubbles. Bakers’ bread and sponge rubber are examples of solid foams. Typical liquid foams are those used in fire-fighting, shaving creams, etc. Foams made by mechanical incorporation of air are widely used in the food industry (e.g. whipped cream, egg white, ice cream, etc.). Foams can be stabilized by surfactants.

fossil fuel    →   fosilno gorivo

Fossil fuels (coal, oil, and natural gas) are the fuels used by man as a source of energy. They are formed from the remains of living organisms and all have a high carbon or hydrogen content. They have value as fuels on the exothermic oxidation of carbon to form carbon dioxide

and the oxidation of hydrogen to form water

fugacity    →   fugacitet

Fugacity (f) is a thermodynamic function used in place of partial pressure in reactions involving real gases and mixtures. For a component of a mixture, it is defined by

where μ is the chemical potential.

The fugacity of a gas is equal to the pressure if the gas is ideal. The fugacity of a liquid or solid is the fugacity of the vapour with which it is in equilibrium. The ratio of the fugacity to the fugacity in some standard state is the activity.

fume hood    →   digestor

Fume hood is a type of local exhaust ventilation system (engineering control). A typical fume hood is cabinet with a moveable front sash (window) made out of safety glass. Air is drawn into the hood under and through the opened sash and is exhausted through openings in the rear and top of the cabinet to a remote point such as an exhaust stack on the roof of the building. A properly used and properly functioning fume hood exhausts hazardous gases, dusts, mists, and vapors from a confined location and helps protect workers from inhalation exposure.

partial pressure    →   parcijalni tlak

Partial pressure is a pressure that one component of gas mixture would have if it were alone in the same volume and at the same temperature as the mixture is in now.

permeability    →   permeabilnost

Permeability (Latin permeare, to pass through) is a passage or diffusion of a gas, vapour, liquid, or solid through a material without physically or chemically affecting it.

gas washing bottle    →   boca ispiralica

Gas washing bottle or Drechsel bottle provide an inexpensive but effective method for washing or drying gases. The gas enters the bottle through the top of the central vertical tube, the lower end of which is below the surface of the washing medium. To maximize surface area contact of the gas to the liquid, a gas stream is slowly blown into the vessel through the fritted glass tip so that it breaks up the gas into many tiny bubbles. After bubbling through the medium, the gas rises to the top and exits through the side tube. It is named after the German chemist Edmund Drechsel (1843-1897).

Geiger counter    →   Geigerov brojač

Geiger counter (Geiger-Muller counter) is a device used to detect and measure ionising radiation. It consists of a tube containing a low-pressure gas (usually argon or neon with methane) and a cylindrical hollow cathode through the centre of which runs a fine-wire anode. A potential difference of about 1 000 V is maintained between the electrodes. An ionising particle or photon passing through a window into the tube will cause an ion to be produced and the high potential will accelerate it towards its appropriate electrode, causing an avalanche of further ionisations by collision. The consequent current pulses can be counted in electronic circuits or simply amplified to work a small loudspeaker in the instrument. It was first devised in 1908 by the German physicist Hans Geiger (1882-1945). Geiger and W. Muller produced an improved design in 1928.

petrochemicals    →   petrokemikalije

Petrochemicals are the industrially important organic chemicals which are derived from petroleum or natural gas.

smog    →   smog

Smog is a mixture of smoke and fog. The term is used to describe city fogs in which there is a large proportion of particulate matter (tiny pieces of carbon from exhausts) and also a high concentration of sulphur and nitrogen gases.