INERT GASES

From Big Medical Encyclopedia

INERT GASES (synonym rare gases) — chemical elements of the main subgroup of the eighth group of a periodic system of D. I. Mendeleyev; differ from other chemical elements in high chemical inertness thanks to what find broad application in various areas of the equipment; are used by drawing up respiratory mixes in anesthesiology.

K I. belong helium (grech, helios sun; He), neon (grech, neos new; Ne), argon (grech, argos not active; Ar), krypton (grech, kryptos hidden; Kr), xenon (grech, xenos others; Xe), radon (originally was called radon — Em and Ni niton; Rn). The main characteristics are provided in the table And.

Table. MAIN PHYSICAL AND CHEMICAL CHARACTERISTICS of INERT GASES


At usual conditions And. are the gases consisting of one-atomic molecules.

J. W. Rayleigh at the end of 19 century established that density of the nitrogen received from air on 0,0067 g • l - 1 it is more than density of the nitrogen received from its chemical connections. W. Ramsay assumed that this deviation is explained by existence in air of unknown heavy gas. In 1894 Ramzay and Rayleigh discovered argon and received it from air. In 1895 Ramzay emitted the helium found in 1868 Zhansenom from mineral of a kleveit (P.-J. - Page of Janssen) spectroscopically in the atmosphere of the Sun. In 1898 Ramzay and the Traverse (M. of W. Travers) differential distillation of a liquid air opened and received neon, krypton and xenon. Radon was found in decomposition products of radium by F. Dorn in 1900.

Ground mass And. is airborne (apprx. 1% on volume); most of all in air of argon (0,934 about. %), least of all — radon (5*10^-8 about. %). Gely contains also as impurity in some natural gases (from 0,85 — 1,8 about. %), in mineral waters and minerals as a radioactive decay product of radioelements. According to a spectral analysis, helium contains in the atmosphere of the Sun, fogs and as a part of substance of some stars.

And. are colourless, have no taste. Helium is among the most difficult liquefied gases; during the cooling to — 271 ° and with a pressure of 38,0 mm of mercury. from the usual state (helium I) it passes into another (helium II), in Krom gains such unusual property as superflowability (viscosity of helium II is 1010 times less than viscosity of water) and the high thermal conductivity exceeding heat conductivity of copper by 100 times.

And. of a rastvorima in water, and their solubility increases with increase in atomic weight (weight). So, e.g., in 100 ml of water at 0 ° 0,94 ml of helium, 5,6 ml of argon and 51 ml of radon are dissolved. Solubility And. in organic solvents in some cases is higher, than in water.

And. in comparison with other gases well carry electric current. At low temperatures And. form colourless crystals which structure can be expressed by a formula E*6N with water 2 O, where E — Ar, Kr, Xe or Rn atom. Stability of these hydrates increases with increase in atomic weight (weight) And., but even the stablest of them — Rn*6H 2 O — breaks up at temperature increase to 0 °. And. have characteristic absorption spectrums that forms a basis of analytical definition And.

Long time was believed, as. are not capable to formation of chemical compounds what also their name confirms, however chemical compounds of krypton, xenon and radon with fluorine were received later (KrF 2 , KrF 4 , XeF 2 , XeF 4 , RnF 4 ) and xenon with oxygen (XeO 3 , XeO 4 ). The majority of these connections represent the crystal substances steady at usual temperature.

And. receive differential distillation of a liquid air. Large amounts of helium receive also from natural geliyenosny gases which along with helium sometimes contain argon and small amounts of neon. Radon is received boiling or pumping out of solutions of salts of radium in which radon collects as a result of disintegration of radium.

At inhalation of the highest And. in mix with oxygen at the person and the highest animals the state similar to intoxication is observed by alcohol.

The anesthetizing and anesthetic effect And. increases with increase in atomic weight (weight) in gas. Argon, helium and krypton have anesthetic effect only at their use under supertension (the largest pressure argon demands). Xenon has the insignificant anesthetizing effect with a usual pressure. In concentration of 60% in mix with oxygen xenon causes an analgesia, in concentration of 80% — causes a loss of consciousness on 2 — the 3rd min. inhalations of mix. However oxygen-xenon mix does not find practical application yet.

And. find the most various application. Helium is used for obtaining very low temperatures and for preparation of artificial air, in Krom nitrogen is replaced with helium (see. prepared atmosphere ). Such «helium» air is applied to breath during the works under the high pressure (diving devices, caissons), and also in anesthesiology and resuscitation, especially in pediatric practice. Use of helium-oxygen mix in these fields of medicine is based that it considerably reduces airway resistance to inhaled air and facilitates work of respiratory muscles. Owing to smaller solubility of helium in blood in comparison with solubility of nitrogen danger of emergence of a caisson disease decreases (see. Compressed-air disease ). Radon (see) use as radioactive drug at treatment of a number of diseases, especially diseases of a musculoskeletal system. In balneological practice (see. Balneoterapiya ) widely apply treatment by the natural and artificially prepared radon waters in the form of bathtubs, irrigations, inhalations, etc.

Ions of helium (alpha particle) widely use for carrying out nuclear reactions. Neon and argon apply to production of advertizing and alarm gazosvetny lamps. Fill with argon usual electrolamps; at the same time power consumption decreases and endurance of threads of an incandescence increases. Argon is applied also as chemically inert environment at different studying of processes. Helium is applied to filling of aeronautic devices (radiosondes, etc.). Though its elevating power is 8% less, than elevating power of hydrogen, it negoryuch also does not form, like hydrogen, explosive mixtures with air.


Bibliography: Glinka N. L. General chemistry, L., 1977; To e e z about m V. Gely, the lane with English, M., 1949; Kempbel Dzh. A. Modern general chemistry, the lane with English, t. 1, M., 1975; P e of m and G. Kurs of inorganic chemistry, the lane with it., t. 1, M., 1972.

V. P. Mishin.

Яндекс.Метрика