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Physical & Chemical properties

Dissociation constant

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Administrative data

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Secondary literature

Data source

Referenceopen allclose all

Reference Type:
review article or handbook
Title:
Synthetic Amorphous Silica (CAS No. 7631-86-9)
Author:
ECETOC
Year:
2006
Bibliographic source:
JACC Report No. 51, European Centre for Ecotoxicology and Toxicology of Chemicals, Brussels, September 2006
Reference Type:
publication
Title:
The structure of the silica/electrolyte interface
Author:
Yates DE, Healy TW
Year:
1976
Bibliographic source:
J Coll Interf Sci 55, 9 - 19 (cited from ECETOC JACC No. 51, 2006)
Reference Type:
review article or handbook
Title:
Hydroxyl groups on silica surfaces
Author:
Burneau A, Gallas JP
Year:
1998
Bibliographic source:
In: The surface properties of silicas (Legrand AP, ed) , Chapter 3, J Wiley and Sons, Chichester, UK, pp 147-234 (cited from ECETOC JACC No. 51)
Reference Type:
review article or handbook
Title:
The Chemistry of Silica
Author:
Iler RK
Year:
1979
Bibliographic source:
John Wiley & Sons, N.Y. 1979 (from Löbbus et al. 1998)

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
There was no guidelines followed.
GLP compliance:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Silicon dioxide
EC Number:
231-545-4
EC Name:
Silicon dioxide
Cas Number:
7631-86-9
Molecular formula:
O2Si
IUPAC Name:
dioxosilane
Specific details on test material used for the study:
Synthetic amorphous silicas:
CAS-No. 112945-52-5, CAS-Name: Silica, amorphous, fumed, crystalline-free;
CAS-No. 112926-00-8, CAS-Name: Silica gel, precipitated, crystalline-free.

Results and discussion

Dissociating properties:
yes
Dissociation constantopen allclose all
pKa:
9.8
Remarks on result:
other: monosilicic acid (orthosilicic acid)
pKa:
7.1
Remarks on result:
other: surface silanol groups

Any other information on results incl. tables

The acidity increases with the degree of polymerisation.

Applicant's summary and conclusion