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Dissociation constant

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Reference
Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010-06-11 to 2010-06-15
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Deviations:
no
Principles of method if other than guideline:
not reported
GLP compliance:
no
Dissociating properties:
yes
pKa:
1.89
Temp.:
20 °C

The system was checked at 20 °C by using a KCl solution 0.01 mol/L.

The sample was measured with seven concentrations.

Concentration

Specific conductivity

Equivalent conductivity

Reciprocal equivalent conductivity

c

κ

Λ

1 / Λ

Mol/L

mS/cm

S cm2/ mol

Mol/S cm2

0.00344

0.302

87.7907

0.01139

0.00172

0.1584

92.0930

0.01086

0.00086

0.0829

96.3953

0.01037

0.00043

0.04335

100.8140

0.00992

0.000215

0.02185

101.6279

0.00984

0.0001075

0.0115

106.7967

0.00935

0.00005375

0.00585

108.8372

0.00919

For further calculation Ostwald dilution law was used:

Result: Ka = 1.30 * 10 -2 mol/L

pKa = 1.89

Description of key information

The dissociation constant is pKa = 1.89 at 20 °C (OECD 112).

Key value for chemical safety assessment

Additional information

The dissociation constant of the substance was determined using conductometric method, in accordance with OECD Guideline 112.