Gay Lussac

Gay[Pg.188]

Charles s law, which is a quite difTerent law, is also sometimes referred to as Gay-Lussac s law. 

Ar. Buraq, Pers. Burah) Boron compounds have been known for thousands of years, but the element was not discovered until 1808 by Sir Humphry Davy and by Gay-Lussac and Thenard. 

L. silex, silicis, flint) Davy in 1800 thought silica to be a compound and not an element later in 1811, Gay Lussac and Thenard probably prepared impure amorphous silicon by heating potassium with silicon tetrafluoride. 

Charles law, also known as Gay-Lussac s law, states that the volume of a given mass of gas varies directly as the absolute temperature if the pressure remains constant, that is. 

Boron trifluoride [7637-07-2] (trifluoroborane), BF, was first reported in 1809 by Gay-Lussac and Thenard (1) who prepared it by the reaction of boric acid and fluorspar at duU red heat. It is a colorless gas when dry, but fumes in the presence of moisture yielding a dense white smoke of irritating, pungent odor. It is widely used as an acid catalyst (2) for many types of organic reactions, especially for the production of polymer and petroleum (qv) products. The gas was first produced commercially in 1936 by the Harshaw Chemical Co. (see also Boron COMPOUNDS). 

Stannous fluoride probably was first prepared by Scheele in 1771 and was described by Gay-Lussac and Thenard in 1809. Commercial production of stannous fluoride is by the reaction of stannous oxide and aqueous hydrofluoric acid, or metallic tin and anhydrous hydrogen fluoride (5,6). Snp2 is also produced by the reaction of tin metal, HP, and a halogen in the presence of a nitrile (7). 

Formic acid [64-18-6] (methanoic acid) is the first member of the homologous series of alkyl carboxyHc acids. It occurs naturally ia the defensive secretions of a number of insects, particularly of ants. Although the acid nature of the vapors above ants nests had been known since at least 1488, the pure acid was not isolated until 1671, when the British chemist John Ray described the isolation of the pure acid by distillation of ants (1). This remained the main preparative method for more than a century until a convenient laboratory method was discovered by Gay-Lussac (2). The preparation of formates using carbon monoxide was described by Berthelot in 1856. 

Silicon [7440-21-3] Si, from the Latin silex, silicis for flint, is the fourteenth element of the Periodic Table, has atomic wt 28.083, and a room temperature density of 2.3 gm /cm. SiUcon is britde, has a gray, metallic luster, and melts at 1412°C. In 1787 Lavoisier suggested that siUca (qv), of which flint is one form, was the oxide of an unknown element. Gay-Lussac and Thenard apparently produced elemental siUcon in 1811 by reducing siUcon tetrafluoride with potassium but did not recognize it as an element. In 1817 BerzeHus reported evidence of siUcon occurring as a precipitate in cast iron. Elemental siUcon does not occur in nature. As a constituent of various minerals, eg, siUca and siUcates such as the feldspars and kaolins, however, siUcon comprises about 28% of the earth s cmst. There are three stable isotopes that occur naturally and several that can be prepared artificially and are radioactive (Table 1) (1). 

Chemical analysis methods maybe used for assay of silver alloys containing no interfering base metals. Nitric acid dissolution of the silver and precipitation as AgCl, or the Gay-Lussac-VoUiard titration methods are used iaterchangeably for the higher concentrations of silver. These procedures have been described (4). 

The interaction forces which account for the value of a in this equation arise from tire size, the molecular vibration frequencies and dipole moments of the molecules. The factor b is only related to the molecular volumes. The molar volume of a gas at one atmosphere pressure is 22.414 ImoD at 273 K, and this volume increases according to Gay-Lussac s law with increasing... 

Charles and Gay-Lussac, working independently, found that gas pressure varied with the absolute temperature. If the volume was maintained constant, the pressure would vary in proportion to the absolute temperature [I j. Using a proportionality constant R, the relationships can be combined to form the equation of state for a perfect gas, otherwi.se known as the perfect gas law. 

Using cm as unit surface and seconds as unit time, n is the number of molecules falling on 1 cm /sec. The number n thus denotes the number of molecules striking each cm of the surface every second, and this number can be calculated using Maxwell s and the Boyle-Gay Lussac equations. The number n is directly related to the speed of the molecules within the system. It is important to realize that the velocity of the molecules is not dependent on the pressure of the gas, but the mean free path is inversely proportional to the pressure. Thus ... 

First donor-acceptor adduct (coordination compound) NH3.BF1 prepared by J. L. Gay Lussac (A. Werner s theory, I89I-5). 

All six possible diatomic compounds between F, Cl, Br and I are known. Indeed, ICl was first made (independently) by J. L. Gay Lussac and H. Davy in 1813-4 soon after the isolation of the parent halogens themselves, and its existence led J. von Liebig to miss the discovery of the new element bromine, which has similar properties (p. 794). The compounds vary considerably in thermal stability CIF is extremely robust ICl and IBr are moderately stable and can be obtained in very pure crystalline form at room temperature BrCl readily dissociates reversibly into its... 

Perhaps the first stoichiometric relationship to be discovered was the law of combining volumes, proposed by Gay-Lussac in 1808 The volume ratio of any two gases in a reaction at constant temperature and pressure is the same as the reacting nude ratio. 

Charles s and Gay-Lussac s law Relation stating that at constant P and n, the volume of a gas is directly proportional to its absolute temperature, 106-107, 111 Chelating agent Complexing ligand that forms more than one bond with a central metal atom the complex formed is called a chelate, 411-412 natural, 424-425 synthetic, 424-425 Chemical equation Expression that describes the nature and relative amounts of reactants and products in a reaction, 60-61. See also Equation, net ionic. 

Gasoline, 583-584 Gay-Lussac, Joseph, 106 General Conference of Weights and Measures, 635... 

The procedure may be illustrated by the following simple experiment, which is a modification of the Gay Lussac-Stas method. The sodium chloride solution is added to the silver solution in the presence of free nitric acid and a small quantity of pure barium nitrate (the latter to assist coagulation of the precipitate). 

If the pressure is maintained constant, the volume is found to increase by approximately the same fraction of the volume at 0° C, for each degree rise of temperature (law of Dalton and Gay-Lussac) ... 

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