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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Physical & Chemical properties

Dissociation constant

Currently viewing:

Administrative data

Endpoint:
dissociation constant
Type of information:
other: handbook
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
Handbook data are considered from a trusted source. The results given are for ammonia and phosphoric acid.

Data source

Reference
Reference Type:
review article or handbook
Title:
Dissociation constants of inorganic substances, 8-44
Author:
Lide, D.R. (ed.)
Year:
1999
Bibliographic source:
CRC Handbook of Chemistry and Physics, 80th ed., 1999-2000, New York: CRC Press.

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
No method given, data taken from the handbook.
GLP compliance:
not specified

Test material

Constituent 1
Reference substance name:
Ammonia NH3
IUPAC Name:
Ammonia NH3
Constituent 2
Chemical structure
Reference substance name:
Orthophosphoric acid
EC Number:
231-633-2
EC Name:
Orthophosphoric acid
Cas Number:
7664-38-2
Molecular formula:
H3O4P
IUPAC Name:
Phosphoric acid
Details on test material:
Ammonia and phosphoric acid were assessed individually. No further details on these substances were provided.

Results and discussion

Dissociation constantopen allclose all
No.:
#1
pKa:
9.25
Temp.:
25 °C
Remarks on result:
other: Ammonia NH3
No.:
#1
pKa:
2.16
Temp.:
25 °C
Remarks on result:
other: phosphoric acid
No.:
#2
pKa:
7.21
Temp.:
25 °C
Remarks on result:
other: phosphoric acid
No.:
#3
pKa:
12.32
Temp.:
25 °C
Remarks on result:
other: phosphoric acid

Applicant's summary and conclusion

Conclusions:
pKa Ammonia: 9.25 
pKa's phosphoric acid: 2.16, 7.21, 12.32