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EC number: 215-158-8 | CAS number: 1308-14-1
Hydrolysis
Administrative data
- Endpoint:
- hydrolysis
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Acceptable, well-documented publication/study report which meets basic scientific principles.
Data source
Reference
- Reference Type:
- publication
- Title:
- Chromium(III)Hydrolysis Constants and Solubility of Chromium(III) Hydroxide
- Author:
- Rai, D.; Sass, B.M. and Moore, D.A.
- Year:
- 1 987
- Bibliographic source:
- Inorganic Chemistry, 2987. 26, 345 - 349
Materials and methods
Test guideline
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Thermodynamical equilibrium constants of hydrolysis reaction steps were determined in solubility experiments depending on pH.
- 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
Study design
- Analytical monitoring:
- yes
Results and discussion
- Transformation products:
- yes
Identity of transformation productsopen allclose all
- No.:
- #1
Reference
- Reference substance name:
- Unnamed
- IUPAC name:
- Cr(OH)2+
- Identifier:
- other: Chemical formula
- Identity:
- Cr(OH)2+
- No.:
- #2
Reference
- Reference substance name:
- Unnamed
- IUPAC name:
- CrOH2+
- Identifier:
- other: Chemical formula
- Identity:
- CrOH2+
- No.:
- #3
Reference
- Reference substance name:
- Unnamed
- IUPAC name:
- Cr3+
- Identifier:
- other: Chemical formula
- Identity:
- Cr3+
- No.:
- #4
Reference
- Reference substance name:
- Unnamed
- IUPAC name:
- H2O
- Identifier:
- other: Chemical formula
- Identity:
- H2O
Any other information on results incl. tables
In acidic solution Cr(III)hydroxide is subject to subsequent hydrolysis at pH<6.8. Based on concentration measurements the thermodynamic equilibrium constants were calculated as follows:
Reaction |
log K |
|
0,01 M* |
0,00 M* |
|
Cr(OH)3(s)+ H+<----> Cr(OH)2++ H2O |
<-0.44 |
<-0.49 |
Cr(OH)3(s)+ 2 H+<----> CrOH2++ 2 H2O |
5.96 ± 0.08 |
5.78 ± 0.08 |
Cr(OH)3(s)+ 3 H+<----> Cr3++ 3 H2O |
<9.76 |
<9.35 |
Between pH 6.8 and 11.5 Cr(OH)3is insoluble and therefore no hydrolysis takes place. As amphoteric hydroxide at high pH < 11.5 , the substance forms hydroxo complexes, see section 4.8 and is soluble again.
The kinetics of precipitation/dissolution of Chromium(III)hydroxide are very rapid.
Applicant's summary and conclusion
- Validity criteria fulfilled:
- not applicable
- Conclusions:
- At low pH < 6.8 Cr(III)hydroxide is hydrolysed very rapidly to soluble species Cr(OH)2+, CrOH2+ and Cr3+. At higher pH, no hydrolysis takes place, as the substance is insoluble. At pH >11.5 hydroxo complexes are formed.
- Executive summary:
In acidic solution Cr(III)hydroxide is subject to subsequent hydrolysis at pH<6.8. Based on concentration measurements the thermodynamic equilibrium constants were calculated as follows:
Reaction
log K
0,01 M*
0,00 M*
Cr(OH)3(s)+ H+<----> Cr(OH)2++ H2O
<-0.44
<-0.49
Cr(OH)3(s)+ 2 H+<----> CrOH2++ 2 H2O
5.96 ± 0.08
5.78 ± 0.08
Cr(OH)3(s)+ 3 H+<----> Cr3++ 3 H2O
<9.76
<9.35
Between pH 6.8 and 11.5 Cr(OH)3ist insoluble and therefore no hydrolysis takes place. As amphoteric hydroxide at high pH < 11.5 , the substance forms hydroxo complexes, see section 4.8 and is soluble again.
The kinetics of precipitation/dissolution of Chromium(III)hydroxide are very rapid.
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