Registration Dossier
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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Diss Factsheets
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EC number: 231-959-5 | CAS number: 7782-50-5
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Endpoint summary
Administrative data
Description of key information
Additional information
Chlorine is a highly reactive compound, which will react readily in the atmosphere and in soil, and with organic matter. In water, chlorine will form hypochlorous acid and hypochlorite at environmental relevant pH. Chlorine discharged to sewer will react to form chloramines. As a non-organic compound, chlorine is not biodegradable.
Photolysis in water
The photolysis half-life of aqueous chlorine in, exposed to summer noon sunlit with clear sky (47°N) at a pH 8 is 12 min when measured at the surface. The half-life
increases with decreasing pH due to the decreasing ratio of OCl-/HOCl to 60 min at pH 5. The pseudo-first-order rate constant for the photolysis of HOCl becomes 2 x 10-4/s and that of OCl-1.2 x 10-3/s. The variation of the rate of photolysis with depth was calculated for water columns exhibiting different light absorption coefficients by taking into account that, for both HOCl and OCl-, the most effective wavelength for photolysis in sunlight is approx. 330 nm. These results show that in water treatment, chlorine photolysis should be minimized whenever possible by operating at low pH, sun shielding or night-time addition of chlorine or avoiding storage in shallow reservoirs. The rate of chlorine photolysis controls the formation of OH radical which acts as a secondary highly reactive photooxidant.On u.v. (255 nm) irradiation both HOCl and OCl- photolyze at comparable rates and slowly enough that chlorine depletion will not occur during the time of irradiation typical in UV disinfection.
Photolysis can also contribute to the depletion of chlorine in atmospheric waters whenever chlorine is formed by (slow) ozonation of chloride.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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