Registration Dossier
Registration Dossier
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EC number: 215-158-8 | CAS number: 1308-14-1
Dissociation constant
Administrative data
- Endpoint:
- dissociation constant
- Type of information:
- calculation (if not (Q)SAR)
- Remarks:
- Migrated phrase: estimated by calculation
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Generally accepted calculation method
Data source
Reference
- Reference Type:
- publication
- Title:
- Oxidation and toxicity of chromium in ultramafic soils in Zimbabwe.
- Author:
- Cooper, G. R. C.
- Year:
- 2 002
- Bibliographic source:
- .Applied geochemistry. Journal of the International Association of Geochemistry and Cosmochemistry 17(8), 2002, 981−986
Materials and methods
Test guideline
- Qualifier:
- according to guideline
- Guideline:
- other: Calculation from the relationship between logK and standard free energy change of reaction.
- GLP compliance:
- not specified
Test material
- Reference substance name:
- Chromium (III) hydroxide
- EC Number:
- 215-158-8
- EC Name:
- Chromium (III) hydroxide
- Cas Number:
- 1308-14-1
- Molecular formula:
- CrH3O3
- IUPAC Name:
- chromium (III) hydroxide
Constituent 1
Results and discussion
- Dissociating properties:
- yes
Dissociation constantopen allclose all
- No.:
- #1
- Remarks on result:
- other: Relevant reaction: Cr(OH)3 <----> Cr3+aq + 3OH- Dissociation is not possible in neutral solution
- No.:
- #2
- Remarks on result:
- other: Under strong acidic conditions dissociation occurs according to the following reaction: Cr(OH)3 + 3 H+ <----> Cr3+aq + 3 H2O
Any other information on results incl. tables
Original values are reported as follows:
Cr(OH)3<----> Cr3+aq+ 3OH- log K = -37.4
Cr(OH)3+ 3 H+<----> Cr3+aq+ 3 H2O logK = 4,6
Equilibrium constants were calculated from the relation between logK and the standard energy change of reaction. Values for free energies of formation were taken from Garrels and Christ (1965) and Weast (1980).
Dissociation is only valid for soluble Cr(OH)3. The solubility of Chromium(III)hydroxide between pH 6.8 and 11.5 is very low. The solubility product is approx. 1 x 10-30.
Applicant's summary and conclusion
- Conclusions:
- Chromium hydroxide subject to dissociation in strongly acidic solution. Dissociation in neutral medium is very low caused by the very low water solubility at pH 6.8 - 11.5 of the substance and the very low equilibrium constant of the dissociation reaction.
- Executive summary:
Equilibrium constants were calculated from the relation between logK and the standard energy change of reaction. Values for free energies of formation were taken from Garrels and Christ (1965) and Weast (1980).
Cr(OH)3<----> Cr3+aq+ 3OH- log K = -37.4
Cr(OH)3+ 3 H+<----> Cr3+aq+ 3 H2O log K = 4,6
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