Vapor-pressure, chlorine

Osmium telroxide (osmic acid [CAS 20816-12-0]) Corrosive upon direct contact severe burns may result. Fumes are highly irritating to eyes and respiratory tract. Based on high-dose animal studies, bone marrow injuiy and kidney damage may occur. 0.0002 ppm (as Os) 1 mg/m (as Os) Coloriess to pale yellow solid with a sharp and irritating odor like chlorine. Vapor pressure is 7 mm Hg at20°C (68°F). Not combustible. Catalyst and laboratory reagent. 

Chlorine, a member of the halogen family, is a greenish yellow gas having a pungent odor at ambient temperatures and pressures and a density 2.5 times that of air. In Hquid form it is clear amber SoHd chlorine forms pale yellow crystals. The principal properties of chlorine are presented in Table 15 additional details are available (77—79). The temperature dependence of the density of gaseous (Fig. 31) and Hquid (Fig. 32) chlorine, and vapor pressure (Fig. 33) are illustrated. Enthalpy pressure data can be found in ref. 78. The vapor pressure P can be calculated in the temperature (T) range of 172—417 K from the Martin-Shin-Kapoor equation (80) ... 

Fig. 33. Vapor pressure of liquid chlorine as a function of temperature (78).

Chlorine Monofluoride. Chlorine monofluoride is a colorless gas that condenses to a Hquid with a slight yeUow cast and free2es to a white soHd. The infrared spectmm of gaseous chlorine monofluoride and the Raman spectmm of the Hquid have been studied (36). The uv-absorption spectmm (37) and vapor pressure data are also available (11). 

Chlorine Pentafluoride. Chlorine pentafluoride is a colorless gas at room temperature. The ir and Raman spectra of the Hquid and gas phase have been studied (34,39). The uv absorption spectmm (45) and vapor pressure data may be found in the Hterature (18). 

Chlorine ttifluoride is commercially available at 99% minimum purity (108) and is shipped as a Hquid under its own vapor pressure in steel cylinders in quantities of 82 kg per cylinder or less. Chlorine ttifluoride is classified as an oxidizer and poison by DOT. 

Halides. Indium trichloride [10025-83-8] InCl, can be made by heating indium in excess chlorine or by chlorinating lower chlorides. It is a white crystalline soHd, deUquescent, soluble in water, and has a high vapor pressure. InCl forms chloroindates, double salts with chlorides of alkaLi metals, and organic bases. 

Health and Safety Factors and Regulations. Iodine is much safer to handle at ordinary temperatures than the other halogens because iodine is a soHd and its vapor pressure is only 1 kPa (7.5 mm Hg) at 25°C, compared to 28.7 kPa (215 mm Hg) for bromine and 700 kPa (6.91 atm) for chlorine. When handling properly packed containers, usual work clothes are sufficient. In the handling of soHd, unpacked iodine, mbber gloves, mbber apron, and safety goggles are recommended. Respirators or masks are also recommended. 

Chlorine heptoxide is more stable than either chlorine monoxide or chlorine dioxide however, the CX C) detonates when heated or subjected to shock. It melts at —91.5°C, bods at 80°C, has a molecular weight of 182.914, a heat of vapori2ation of 34.7 kj/mol (8.29 kcal/mol), and, at 0°C, a vapor pressure of 3.2 kPa (23.7 mm Hg) and a density of 1.86 g/mL (14,15). The infrared spectmm is consistent with the stmcture O CIOCIO (16). Cl O decomposes to chlorine and oxygen at low (0.2—10.7 kPa (1.5—80 mm Hg)) pressures and in a temperature range of 100—120°C (17). It is soluble in ben2ene, slowly attacking the solvent with water to form perchloric acid it also reacts with iodine to form iodine pentoxide and explodes on contact with a flame or by percussion. Reaction with olefins yields the impact-sensitive alkyl perchlorates (18). 

Chlorine fluxing of aluminum to remove hydrogen and undesirable metallic impurities has largely been supplanted by fumeless fluxing procedures, which generally employ a low vapor pressure melt of alkaU chlorides containing a small amount of aluminum chloride as the active ingredient. 

The gases used in the CVD reactor may be either commercially available gases in tanks, such as Ar, N2, WF, SiH, B2H, H2, and NH Hquids such as chlorides and carbonyls or soflds such as Mo carbonyl, which has a vapor pressure of 10 Pa (75 mtorr) at 20°C and decomposes at >150° C. Vapor may also come from reactive-bed sources where a flowing haUde, such as chlorine, reacts with a hot-bed material, such as chromium or tantalum, to give a gaseous species. 

Titanium tetrachloride is completely miscible with chlorine. The dissolution obeys Henry s law, ie, the mole fraction of chlorine ia a solutioa of titanium tetrachloride is proportional to the chlorine partial pressure ia the vapor phase. The heat of solutioa is 16.7 kJ/mol (3.99 kcal/mol). The appareat maximum solubiUties of chlorine at 15.45 kPa (116 mm Hg) total pressure foUow. 

Organic compounds of bromine usually resemble their chlorine analogues but have higher densities and lower vapor pressures. The bromo compounds are more reactive toward alkaUes and metals brominated solvents should generally be kept from contact with active metals such as aluminum. On the other hand, they present less fire hazard one bromine atom per molecule reduces flammabiUty about as much as two chlorine atoms. 

Hypochlorous acid and chlorine monoxide coexist in the vapor phase (78—81). Vapor pressure measurements of aqueous HOCl solutions show that HOCl is the main chlorine species in the vapor phase over <1% solutions (82), whereas at higher concentrations, CI2O becomes dominant (83). The equihbtium constant at 25°C for the gas-phase reaction, determined by ir and uv spectrophotometry and mass spectrometry, is ca 0.08 (9,66,67,69). The forward reaction is much slower than the reverse reaction. 

The surface area of a spill should be minimized for materials that are highly toxic and have a significant vapor pressure at ambient conditions, such as acrylonitrile or chlorine. This will make it easier and more practical to collect vapor from a spill or to suppress vapor release with foam. This may require a deeper nondrained dike area than normal or some other design that wilfminimize surface area, in order to contain the required volume. It is usually not desirable to cover a diked area to restric t loss of vapor if the spill consists of a flammable or combustible material. 

Volatile organic compounds (VOCs) include organic compounds with appreciable vapor pressure. They make up a major class of air pollutants.I his class includes not only pure hydrocarbons but also partially oxidized hydrocarbons (organic acids, aldehydes, ketones), as well as organics containing chlorine, sulfur, nitrogen, or other atoms in the molecule. 

The vapor pressure of chlorine dioxide, Cl02, is 155 Torr at —22.75°C and 485 Torr at ().()0°C. Calculate (a) the standard enthalpy of vaporization (b) the standard entropy of vaporization (c) the standard Gibbs free energy of vaporization (d) the normal boiling point of C102. 

A. How much time is required to collect 20.0 1 of chlorine if the gas is collected over water at 20.0°C and the total pressure is 770. Torr Assume that the water is already saturated with chlorine, and so no more dissolves. See Table 8.3 for the vapor pressure of warer. 

PCBs were hrst produced commercially around 1930. The commercial products are complex mixtures of congeners, generated by the chlorination of biphenyl. Most of them are very stable viscous liquids, of low electrical conductivity and low vapor pressure. Their principal commercial applications have been... 

PCB mixtures were once used for a variety of purposes, and came to cause widespread environmental pollution. Over 100 different congeners are present in commercial products such as Aroclor 1248 and Aroclor 1254. PCBs are lipophilic, stable, and of low vapor pressure. Many of the more highly chlorinated PCBs are refractory, showing very strong biomagnification with movement along food chains. 

The van t Hoff equation also has been used to describe the temperature effect on Henry s law constant over a narrow range for volatile chlorinated organic chemicals (Ashworth et al. 1988) and chlorobenzenes, polychlorinated biphenyls, and polynuclear aromatic hydrocarbons (ten Hulscher et al. 1992, Alaee et al. 1996). Henry s law constant can be expressed as the ratio of vapor pressure to solubility, i.e., pic or plx for dilute solutions. Note that since H is expressed using a volumetric concentration, it is also affected by the effect of temperature on liquid density whereas kH using mole fraction is unaffected by liquid density (Tucker and Christian 1979), thus... 

As described earlier, Henry s law constants can be calculated from the ratio of vapor pressure and aqueous solubility. Henry s law constants do not show a simple linear pattern as solubility, Kqw or vapor pressure when plotted against simple molecular descriptors, such as numbers of chlorine or Le Bas molar volume, e.g., PCBs (Burkhard et al. 1985b), pesticides (Suntio et al. 1988), and chlorinated dioxins (Shiu et al. 1988). Henry s law constants can be estimated from ... 

The vapor pressure data in Figure 1.7.11 show a slope of about 0.60 log units per 20.9 cm3/mol (i.e., a factor or 4.0) per chlorine. There is a lower slope for the alkylphenols, and they usually have higher vapor pressures, especially for the larger molecules. 

Liu, K., Dickhut, R.M. (1994) Saturation vapor pressures and thermodynamic properties of benzene and selected chlorinated benzenes at environmental temperatures. Chemosphere 29, 581-589. 

Despite endrin s low vapor pressure of 2.0xlCl7 mm Hg (EPA 198la), initial volatilization of 20-30% after agricultural application to soil has been reported to be rapid (Nash 1983). Within 11 days, however, further volatilization was no longer detected (Nash 1983). Unlike some other chlorinated pesticides, endrin volatilization was not enhanced after a rainfall. Small amounts of endrin in soil may also be transported to the air by dust particles. 

Organophosphates (Fig. 10, Table 3) are more toxic than chlorinated hydrocarbons, in particular to humans,but they exhibit lower persistence in soils and do not seem to accumulate in soil fauna or concentrate in birds and fish [74]. This behavior is also related to an enhanced water solubility and lower vapor pressure of organophosphates. Malathion and Parathion (Fig. 10, Table 3) insecticides are known to be chemically hydrolyzed and biodegraded by micro-... 

Vapor pressure (i.e., VP) is a measure of the amount of contaminant present in the air at a particular temperature (see Sect. 2.1.2). VP is one of the main factors controlling the vaporization of PCBs from aqueous or solid phase environments into the atmosphere. Figure 7 shows the vapor pressure at 25 °C for PCB isomers, indicating that VP decreases as the degree of chlorination increases. 

All PCDD/F isomers are solids with high melting points, but low vapor pressure and low solubihty in water. The high octanol-water coefficients are an indication of the observed bioaccumulative behavior in plants and animals for these compounds. Detailed environmentally important physicochemical properties can be found in the literature. All higher chlorinated compounds are very persistent in the environment with half-lives of 5-10 years photolysis with sunlight is the only degradation process in the environment. 

---