Chlorine hydrate composition

As follows from his laboratory notes, the first discovered clathrate hydrate (of chlorine) was observed, but not recognized, by Davy in 1810. Then Cl2, Br2, so2) co2, ch3ci, ch4, c2h, and numerous other gases were shown to form clathrate hydrates [22, 23]. Contrary to inorganic stoichiometric hydrates, those involving hydrocarbons are both non-stoichiometric and crystalline. In addition, gas hydrate composition was found to depend on temperature, pressure, and some... 

Ditte and Maumene disputed the composition of chlorine hydrates... 

In Table 1.2, the following pattern was often repeated (1) the discovery of a new hydrate was published by an investigator (2) a second researcher disputed the composition proposed by the original investigator and (3) a third (or more) investigator(s) refined the measurements made by the initial two investigators, and proposed slight extensions. As a typical example, in the case of chlorine hydrate after Davy s discovery in 1810, Faraday confirmed the hydrate (1823) but proposed that there were ten water molecules per molecule of chlorine. Then Ditte (1882), Maumene (1883), and Roozeboom (1884) re-examined the ratio of water to chlorine. 

A system which encloses, simultaneously, an aqueous solution of a gas, a mixture of this gas with water vapor, and a definite solid compound formed by the union of the gas and water is in equilibrium, at each temperature, when the pressure has a definite value the liquid mixture and the gaseous mixture has, at the same time, a definite composition the total mass of gas and the total mass of water contained in the system do not influence either this tension nor this composition this law was first recognized by Isambert in studying the dissociation of chlorine hydrate the curves of transformation tension of a great number... 

Michael Faraday confirms Davy s observation and determines the composition of chlorine hydrate. 

Faraday made an analysis of chlorine hydrate (recognised as a compoimd by Davy, see p. 56), finding the composition ClgjioHjO. He showed the results to Davy, who suggested that he should heat this compound in a sealed tube. The result was the liquefaction of chlorine, reported in a note at the end of the paper, which also says when perfectly dry chlorine is condensed into a tube by means of a syringe, a portion of it assumes the liquid forni imder a pressure equal to that of 4 or 5 atmospheres this is also mentioned in the paper on fluid chlorine there the pressure is said to have been developed by throwing in air . In an account (which Faraday later said was accurate) Dr. Paris says that on 5 March 1823, on his way to dine with Davy, he called at the Royal Institution and fotmd Faraday carrying out the experiment si ested by Davy. He drew Faraday s attention to what seemed to be oil in the sealed tube. Faraday was surprised and filed off the end of the tube, which exploded. 

The reactor effluent, containing 1—2% hydrazine, ammonia, sodium chloride, and water, is preheated and sent to the ammonia recovery system, which consists of two columns. In the first column, ammonia goes overhead under pressure and recycles to the anhydrous ammonia storage tank. In the second column, some water and final traces of ammonia are removed overhead. The bottoms from this column, consisting of water, sodium chloride, and hydrazine, are sent to an evaporating crystallizer where sodium chloride (and the slight excess of sodium hydroxide) is removed from the system as a soHd. Vapors from the crystallizer flow to the hydrate column where water is removed overhead. The bottom stream from this column is close to the hydrazine—water azeotrope composition. Standard materials of constmction may be used for handling chlorine, caustic, and sodium hypochlorite. For all surfaces in contact with hydrazine, however, the preferred material of constmction is 304 L stainless steel. 

The action of hydrogen peroxide on freshly precipitated hydrated Ti(IV) oxide or the hydrolysis of a peroxide compound such as K2[Ti(02)(S0 2] yields, after drying, a yellow soHd, stable below 0°C, of composition TiO 2H2O. There is one peroxo group per titanium, but the precise stmcture is not known. The yellow soHd loses oxygen and water when heated and Hberates chlorine from hydrochloric acid. When freshly prepared, it is stable in acid or alkah, giving peroxy salts. 

Calcium Hypochlorite. High assay calcium hypochlorite [7778-54-3] was first commercialized in the United States in 1928 by Mathieson Alkali Works, Inc. (now Olin Corp.) under the trade name HTH. It is now produced by two additional manufacturers in North America (Table 5). Historically, it usually contained about 1% water and 70—74% av CI2, so-called anhydrous product, but in 1970, a hydrated product was introduced (234). It is similar in composition to anhydrous Ca(OCl)2 except for its higher water content of about 6—12% and a slightly lower available chlorine content. This product has improved resistance to accidental initiation of self-sustained decomposition by a Ht match, a Ht cigarette, or a small amount of organic contamination. U.S. production in the 1990s consists primarily of partially hydrated Ca(OCl)2, which is sold as a 65% av CI2 product mainly for swimming pool use. Calcium hypochlorite is also sold as a 50% av CI2 product as a sanitizer used by dairy and food industries and in the home, and as a 32% product for mildew control. 

Molecular as well as ionic substances can form hydrates, but of an entirely different nature. In these crystals, sometimes referred to as clathrates, a molecule (such as CFI4, CHCI3) is quite literally trapped in an ice-like cage of water molecules. Perhaps the best-known molecular hydrate is that of chlorine, which has the approximate composition Cl2- 7.3H20. This compound was discovered by the great... 

O Neil JR (1986) Theoretical and experimental aspects of isotopic fractionation. Rev Mineral 16 1-40 Oi T (2000) Calculations of reduced partition function ratios of monomeric and dimeric boric acids and borates by the ab initio molecular orbital theory. J Nuclear Sci Tech 37 166-172 Oi T, Nomura M, Musashi M, Ossaka T, Okamoto M, Kakihana H (1989) Boron isotopic composition of some boron minerals. Geochim Cosmochim Acta 53 3189-3195 Oi T, Yanase S (2001) Calculations of reduced partition function ratios of hydrated monoborate anion by the ab initio molecular orbital theory. J Nuclear Sci Tech 38 429-432 Paneth P (2003) Chlorine kinetic isotope effects on enzymatic dehalogenations. Accounts Chem Res 36 120-126... 

The period from 1810 to 1900 is characterized by efforts of direct composition measurements with inorganic hydrate formers, especially bromine, inorganics containing sulfur, chlorine, and phosphorus, and carbon dioxide. Other notable work listed in Table 1.2 was done by Cailletet and Bordet (1882), who first measured hydrates with mixtures of two components. Cailletet (1877) was also the first to measure a decrease in gas pressure when hydrates were formed in a closed chamber, using a precursor of an apparatus still in use at the Technical University of Delft, the Netherlands. 

Glew (1959) suggested that the most nonstoichiometric guest molecules are those for which the size of the guest approaches the upper limit of the free volume of a cavity. For two molecules that approach the size limit of cavities, Glew and Rath (1966) presented experimental evidence that hydrate nonstoichiometry for both chlorine and ethylene oxide was due to the composition of the phase in equilibrium with the hydrates. 

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