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Diss Factsheets
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EC number: 236-743-4 | CAS number: 13472-45-2
- 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
Dissociation constant
Administrative data
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- data from handbook or collection of data
- Remarks:
- The equilibrium constant was estimated using VISUAL MINTEQ Version 2.3. Very few details were provided regarding the modeling process; however, data were obtained from peer-reviewed handbook or collection of data.
- Principles of method if other than guideline:
- The equilibrium constant was estimated using VISUAL MINTEQ Version 2.3 based on a 0.005 M total concentration of sodium tungstate in a 0.01 M solutions of NaCl, allowing solid species to precipitate.
- GLP compliance:
- no
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 8.7
- Temp.:
- 20 °C
- Remarks on result:
- other: Estimate using VISUAL MINTEQ Version 2.3 based on a 0.005 M total concentration of sodium tungstate in a 0.01 M solutions of NaCl, allowing solid species to precipitate, assumed to be conducted at room temperature.
- No.:
- #2
- pKa:
- 65.16
- Temp.:
- 20 °C
- Remarks on result:
- other: Estimate using VISUAL MINTEQ Version 2.3 based on a 0.005 M total concentration of sodium tungstate in a 0.01 M solutions of NaCl, allowing solid species to precipitate, assumed to be conducted at room temperature.
- No.:
- #3
- pKa:
- 3.62
- Temp.:
- 20 °C
- Remarks on result:
- other: Estimate using VISUAL MINTEQ Version 2.3 based on a 0.005 M total concentration of sodium tungstate in a 0.01 M solutions of NaCl, allowing solid species to precipitate, assumed to be conducted at room temperature.
- No.:
- #4
- pKa:
- 71.24
- Temp.:
- 20 °C
- Remarks on result:
- other: Estimate using VISUAL MINTEQ Version 2.3 based on a 0.005 M total concentration of sodium tungstate in a 0.01 M solutions of NaCl, allowing solid species to precipitate, assumed to be conducted at room temperature.
- No.:
- #5
- pKa:
- 48.4
- Temp.:
- 20 °C
- Remarks on result:
- other: Estimate using VISUAL MINTEQ Version 2.3 based on a 0.005 M total concentration of sodium tungstate in a 0.01 M solutions of NaCl, allowing solid species to precipitate, assumed to be conducted at room temperature.
- No.:
- #6
- pKa:
- 111.5
- Temp.:
- 20 °C
- Remarks on result:
- other: Estimate using VISUAL MINTEQ Version 2.3 based on a 0.005 M total concentration of sodium tungstate in a 0.01 M solutions of NaCl, allowing solid species to precipitate, assumed to be conducted at room temperature.
- Conclusions:
- Dissociation constants of tungsten species ranged from pKa 3.62 to 111.5 when estimated using VISUAL MINTEQ Version 2.3 based on a 0.005 M total concentration of sodium tungstate in a 0.01 M solutions of NaCl, allowing solid species to precipitate.
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- data from handbook or collection of data
- Principles of method if other than guideline:
- Equilibrium constants were estimated for dilute solutions at 25 degrees C.
- GLP compliance:
- not specified
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 3
- Temp.:
- 25 °C
- Remarks on result:
- other: see remarks on results for equations
- No.:
- #2
- pKa:
- 12.25
- Temp.:
- 25 °C
- Remarks on result:
- other: see remarks on results for equations
- No.:
- #3
- pKa:
- 15.8
- Temp.:
- 25 °C
- Remarks on result:
- other: see remarks on results for equations
- No.:
- #4
- pKa:
- 3.5
- Temp.:
- 25 °C
- Remarks on result:
- other: see remarks on results for equations
- No.:
- #5
- pKa:
- 8.1
- Temp.:
- 25 °C
- Remarks on result:
- other: see remarks on results for equations
- No.:
- #6
- pKa:
- 13.4
- Temp.:
- 25 °C
- Remarks on result:
- other: see remarks on results for equations
- Conclusions:
- Dissociation constants of tungsten species ranged from pKa 3.0 to 15.8 in dilute solutions at 25 deg. C.
Referenceopen allclose all
Reactions represented by pKas above:
No. | Reaction | pK |
1 | WO42-+ 2H+= WO3(H2O)aq |
8.7 |
2 | WO42-+ 8H+= W7O246- + 4H2O |
65.16 |
3 | WO42-+ H+= HWO4- |
3.62 |
4 | 7WO42-+ 9H+= HW7O245- + 4H2O |
71.24 |
5 | 6WO42-+ 6H+= H2W6O226- +2H2O |
48.4 |
6 | 12WO42-+ 14H+= H2W12O4210- + 6H2O |
111.5 |
Reactions represented by pKas above:
No. | Reaction | log K | pKa |
1 | W+ 4H2O= WO42-+ 8H+ + 6e | -3.0 | 3.0 |
2 | alpha-WO3 +H2O = WO42-+ 2H+ | -12.25 | 12.25 |
3 | H2WO4(s) = WO42-+ 2H+ | -15.8 | 15.8 |
4 | HWO4- = WO42-+ 2H+ | -3.5 | 3.5 |
5 | H2WO4(aq) = WO42-+ 2H+ | -8.1 | 8.1 |
6 | WO2 + 2H2O = WO42- + 4H+ + 2e | -13.4 | 13.4 |
Description of key information
The speciation of tungsten compounds in water is complex and several species exist together, depending on the pH of the system. Sodium tungstate is soluble and dissolution will occur at environmentally relevant pHs according to the Transformation/Dissolution testing (IUCLID endpoint 4.8, CSR section 1.3). The endpoint study records indicate that the pKa for species generated in an aqueous solution of sodium tungstate range from 3-115. The pKa for the dissociation of HWO4- = WO42-+ 2H+ is equal to 3.5, while the pKa of H2WO4(aq) = WO42-+ 2H+ is 8.1.
Key value for chemical safety assessment
- pKa at 20°C:
- 3.5
Additional information
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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