Chemical Fact Sheet
Chlorine
| Chemical Abstract Number (CAS #) | 7782-50-5 |
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| Synonyms | BERTHOLITE; CHLOOR- (DUTCH); CHLOR- (GERMAN); CHLORE- (FRENCH); CHLORINE-MOL; CLORO- (ITALIAN&SPANISH); MOLECULAR-CHLORINE; Caswell-No-179; EPA-Pesticide-Chemical-Code-020501 |
| Analytical Methods | SM4500CI |
| Molecular Formula | CI |
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Synopsis
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Chlorine-(Gr. chloros, greenish yellow), Cl; at. wt. 35.4527(9); at. no. 17; m.p. -101.5 deg C; b.p. -34.04 deg C; density 3.214 g/l; sp. gr. 1.56 (-33.6 deg C); valence 1,3,5, or 7. Discovered in 1774 by Scheele, who thought it contained oxygen; named in 1810 by Davy, who insisted it was an element. In nature it is found in the combined state only, chiefly with sodium as common salt (NaCI), carnallite (KMgCl3 - 6H20), and sylvite (KCl). It is a member of the halogen (salt-forming) group of elements and is obtained from chlorides by the action of oxidizing agents and more often by electrolysis; it is a greenish-yellow gas, combining directly with nearly all elements. At 1O deg C one volume of water dissolves 3.10 volumes of chlorine, at 30 deg C only 1.77 volumes. Chlorine is widely used in making many everyday products. It is used for producing safe drinking water the world over. Even the smallest water supplies are now usually chlorinated. It is also extensively used in the production of paper products, dyestuffs, textiles, petroleum products, medicines, antiseptics, insecticides, foodstuffs, solvents, paints, plastics, and many other consumer products. Most of the chlorine produced is used in the manufacture of chlorinated compounds for sanitation, pulp bleaching, disinfectants, and textile processing. Further use is in the manufacture of chlorates, chloroform, carbon tetrachloride, and in the extraction of bromine. Organic chemistry demands much from chlorine, both as an oxidizing agent and in substitution, since it often brings desired properties in an organic compound when substituted for hydrogen, as in one form of synthetic rubber. Chlorine is a respiratory irritant. The gas irritates the mucous membranes and the liquid burns the skin. As little as 3.5 ppm can be detected as an odor, and 1000 ppm is likely to be fatal after a few deep breaths. It was used as a war gas in 1915. Natural chlorine contains two isotopes. Sixteen other isotopes and isomers are known. |
| Use | MANUFACTURE CHLORINATED LIME USED IN BLEACHING ALL KINDS OF FABRIC; MANUFACTURE SYNTHETIC RUBBER & PLASTICS; FOR PURIFYING WATER; DETINNING & DEZINCING IRON; DISINFECTING Used to bleach woodpulp Manufacture of chlorinated hydrocarbons, polyvinyl chloride, ethylene dichloride hypochlorous acid, chlorobenzene, chlorinated lime, water purification, shrink-proofing wool; in flame-retardant cmpd; in special batteries (with lithium or zinc); processing of meat, fish, vegetables, and fruit. Manufacture of carbon tetrachloride, ethylene and propylene oxides, glycols, trichloroethylene, perchloroethylene, chloroform, vinylidene chloride, polychloroprene, hydrogen chloride, metal chlorides, chloracetic acid, chloral, synthetic glycerine, methyl chlorides, chlorinated benzenes, tetraethyl lead, fluorine compounds, titanium tetrachloride, monochloroacetic acid, phosgene, chloroisocyanuric acid, phosphorus chloride, dichlorobutene, and chlorinated paraffins. Agent used to control biofouling in cooling systems. Fungicidal foot baths, root canal or tooth extraction, irrigation, or wound sterilization. Cleaning dairy equipment. Manufacture of pesticides, antifreeze, refrigerants, antiknock compounds, plastics, and resins. Odor control and demulsifier in treatment of water. Disinfectant in laundries and dishwater. Aqueous chlorine is effective in reducing surface spoilage bacterial counts on carcasses of slaughter animals and is presently being used for washing beef, pork, lamb, and poultry in some plants under interim authorization. For paper bleaching. Use for the disinfection of relatively clean impervious surfaces, such as babies' feeding bottles, bath, wash-basins, trolleys, and food equipment. |
| Consumption Patterns | 36% USED AS AN INTERMED FOR CHLORINATED ORG CMPD EXCEPT VINYL CHLORIDE AND EPICHLOROHYDRIN; 20% FOR VINYL CHLORIDE; 10% AS AN INTERMED FOR INORG CHEM; 4% FOR EPICHLOROHYDRIN; 20% IN MANUFACTURE OF PULP AND PAPER; 5% IN WATER AND WASTE TREATMENT; AND 5% IN MISC APPLICATIONS (1974). Ethylene dichloride/vinyl chloride monomer, 21%; Pulp and paper, 17%; Inorganic chemicals, 15%; Chloroethanes, 10%; Chloromethanes, 8%; Other organic chemicals (including propylene oxide), 18%; Water treatment, 5%; Miscellaneous, 6% (1986). CHEMICAL PROFILE: Chlorine. Ethylene dichloride/vinyl chloride monomer, 28%; pulp and paper, 18%; inorganic chemicals, 8%; chloromethanes, 7%; chloroethanes, 6%; other organic chemicals (including propylene oxide), 20%; water treatment, 6%; miscellaneous, 7%. CHEMICAL PROFILE: Chlorine. Demand: 1988: 11.6 million tons (31,780 tons per day); 1989: 11.7 million tons (32,050 tons per day); 1993 /projected/: 12 million tons (32,880 tons per day). (Includes exports, which totaled 128 million lb last year, but not imports, which amounted to 619 million lb last year.) |
| Apparent Color | GREENISH-YELLOW, DIATOMIC GAS |
| Odor | SUFFOCATING; Pungent, irritating |
| Boiling Point | -34.6 DEG C |
| Melting Point | -100.98 DEG C |
| Molecular Weight | 70.906 |
| Density | (LIQUID) 1.5649 @ -35 DEG C, 0.9949 ATM; 1.4085 @ 20 DEG C, 6.864 ATM |
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Odor Threshold Concentration |
Water odor threshold: 0.0020 mg/l. Air odor threshold: 0.31 ppm. Odor Safety Class: C. C= Odor safety factor from 1-26. Less than 50% of distracted persons perceive warning of threshold limit value. 0.02-0.2 ppm. Low odor threshold= 0.0300 mg/cu m. High odor threshold= 15.0000 mg/cu m. Irritating concn= 9.00 mg/cu m. |
| Sensitivity Data | Irritating to nose & throat at 5 ppm or above. Highly irritating especially to the mucous membranes of the eyes and respiratory tract. |
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Chemical and Physical Properties |
DISSOCIATION ENERGY (25 DEG C)= 57.978 KCAL; NATURAL ISOTOPES: 35 (75.53%); 37 (24.47%); HEAT CAPACITY (GAS, 25 DEG C) 8.11 CAL/MOLE/DEG C; ACTS AS ELECTRON-ACCEPTOR IN FORMING COMPLEXES WITH MANY DONOR SPECIES; COMBINES READILY WITH ALL ELEMENTS EXCEPT THE RARE GASES (XENON EXCLUDED) & NITROGEN Heat of fusion: 1531 cal/gmole; 22.8 cal/g. Heat of formation: -5.6 kcal/mole @ 25 deg C. Liquefaction pressure: 7.86 atm @ 25 deg C & 1 atm at -35 deg C; Critical vol: 1.763 l/kg; strongly electronegative; 1 l of liq= 456.8 l of gas @ 0 deg C and 1 atm. Ratio of Specific Heats of Vapor (Gas): 1.325. Chlorine weighs 13 lb/gal. Diffusivity: 1.44x10-5 sq cm/s in water at 25 deg C (calculated). Saturation concentration: 882.3 g/cu m at -7 deg C. Heat capacity: constant pressure (cp): 0.473 kj/kg deg C; constant volume (cv): 0.348 kj/kg deg C. Dielectric constant (gas): 1.0005480 at 101.325 kPa @ 20 deg C; dielectric constant (liquid): 1.454 @ 70.15 K Critical volume: 3.216 cu dm/kg Critical density: 0.311 kg/cu m One l of liquid chlorine produces 434 l of chlorine gas at 25 deg C. Saturated vapor pressure: 74.040 lb/sq inch at 50 deg F. Saturated vapor density: 0.95960 lb/cu ft at 50 deg F. Ideal gas heat capacity: 0.114 btu/lb-deg F at 75 deg F. Diffusion coefficient: 0.033 sq m/hr (calculated). Ionization potential: 11.48 eV. RHOMBIC CRYSTALS (TEMPERATURE AND PRESSURE CONDITIONS NOT GIVEN.) Amber liquid (Temperature and pressure conditions not given.) Viscosity: 0.385 cp at 0 deg C /Chlorine, liquid. |
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Environmental Impact |
MUNICIPAL WASTEWATER EFFLUENTS ARE DISCHARGED INTO RIVERS TO MINIMIZE POTENTIAL TOXIC EFFECTS OF MATERIALS SUCH AS RESIDUAL CHLORINE ON AQUATIC BIOTA. ANALYTICAL EXPRESSIONS WERE DERIVED TO EST CRITICAL DISTANCE, CONCN, & ALLOWABLE EFFLUENT CONCN TO MEET INSTREAM CRITERIA. Exposures most commonly result from either storage or transportation accidents involving the pressurized liquid form. Other poisonings occur in industrial accidents, school chemistry experiments, accidental release of chlorine from swimming pool operations, and mixing of cleaning agents (adding acidic cleaning agents to hypochlorite bleach releases chlorine gases). |
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Environmental Fate |
Chlorine makes up approximately 0.0314% of the upper earth's crust. The solid underground contains chlorine mainly in the form of sodium, potassium, and magnesium chlorides. There are no known natural sources of gaseous chlorine. Toxic substances present in uranium enrichment plants include Chlorine. Emission samples were obtained from two medium sized power plants, one fired with heavy fuel oil (0.06% ash, 2% sulfur) and the other with pulverized coal (13% ash, 0.8% sulfur). The coal fired boiler was found to contain chlorine in emission particles. The most important manmade emissions of chlorine are from processes involving the production, transportation, and use of chlorine. The stability of free chlorine in natural water is very low because it is a strong oxidizing agent and rapidly oxidizes inorganic compounds. It also oxidizes organic compounds, but more slowly than inorganic compounds. CHLORINE REACTS WITH ORGANIC PRECURSORS THAT ARE FOUND IN MANY SOURCE WATERS TO PRODUCE A POTENTIAL CARCINOGEN, SUCH AS CHLOROFORM (CHCL3). The presence of light, even in intensities of only a few percent of full mid-day sun, may effect significantly both the rate and mechanism of the dissipation of chlorine in seawater. Light increases the rate of dissipation of hypobromite formed from the added bromine. Bromate is also a product formed when chlorinated seawater is exposed to light, and its rate increases with increasing light intensities. Chlorination studies conducted on natural and artificial seawater, have shown two phases of chlorine losses in seawater: a rapid initial loss followed by a continuous loss at a sharply reduced rate. The initial loss reaches a saturation level that varies widely between natural seawater samples and appears to be related to a true organic demand. Losses continue over 10 day periods and are pronounced in seawater containing bromine. Other studies have indicated that the loss of chlorine is associated with the bromide chemical system in seawater. The fate of the lost chlorine was not determined. Chlorine is highly toxic to all forms of aquatic life, there is no potential for bioaccumulation or bioconcentration. Chlorine bleached flour cake has 131-189 mg/kg of chloride per 100 g of flour. |
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Drinking Water Impact |
Finished water from different USA cities chlorine levels: Cincinnati, 2.7 mg/l; Miami, 2.3 mg/l; Ottumwa, 1.4 mg/l; Philadelphia, 2.0 mg/l and Seattle, 0.0 mg/l. The National Organics Reconnaissance Survey (NORS) tested 80 water supplies throughout the United States, of which 20% were ground water, 33% were lakes & reservoirs, and 47% were rivers. 99% of the utilities used chlorination somewhere in their treatment system. Sixty facilities practiced raw water chlorination; of these sites, 86% applied chlorine at a range of 1-6 mg/l with 34% at 0-2 mg/l, 26% at 2-4 mg/l and 26% at 4-6 mg/l. Free residual levels were 0-0.4 mg/l for 41%; 0.4-0.8 mg/l for 19%, 0.2-0.8 mg/l for 4% and 1.2-1.6 mg/l for 20% of the 80 locations. Combined residual levels of 0-0.4 mg/l accounted for 60% of the locations, 0.4-0.8 mg/l accounted for 20% of the sites and remaining sites had levels from 0.8-2.8 mg/l. Chlorine application in water treatment facilities serving 19 Massachusetts communities ranged from a minimum of 4.3 mg/l to a maximum of 29.7 mg/l with a mean of 15.2 + or - 7.44 mg/l. These treatment levels produced finished water with a free residual chlorine levels at a mean of 1.3 mg/l; the minimum was 0.3 mg/l and the maximum was 4.0 mg/l. Maximum total residual chlorine amounted to 6.0 mg/l, with a minimum of 0.4 mg/l and a mean of 1.5 mg/l. Levels in the distribution system ranged from 0.0-2.0 mg/l for free residual chlorine and from 0.0-2.5 mg/l for total residual chlorine. |
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Disposal |
At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices. /Dispose the contents of a leaking cylinder to a safe out-of-doors area or a hood with forced ventilation. Attach an appropriate control valve provided with a trap or check valve and a long piece of flexible hose connected to the valve outlet. Discharge the gas at a moderate rate into an adequate amount of about 15% aqueous sodium hydroxide or other alkali in a suitable container. When all the gas has been discharged, close the cylinder valve, and transport the resulting salt solution to the plant treating unit for neutralization and disposal. The cylinder should be tagged as defective and returned to the supplier according to their directions. Introduce into large volume and soln of reducing agent (bisulfite, ferrous salts or hypo), neutralize. Recovery is an option to disposal for chlorine in the case of gases from aluminum chloride electrolysis and chlorine in wastewaters. |
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Atmosphere |
Mean ambient air levels: 1-3.7 mg/cu m (0.344 and 1.27 ppm). Atmospheric levels of approximately 0.001 ppm (2.9 ug/cu m) have been measured from coastal areas, and ambient levels in metropolitan areas such as Cincinnati or Baltimore average 0.02 ppm (58.0 ug/cu m). |
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