32
3 Technetium Coordinated by Inorganic Ligands in Aqueous …
Table 3.1 Mean molar activity coefficients and water activity for NaTcO 4 and HTcO 4 solutions
at 25 °C (Rard and Miller 1991)
Molality/mol·kg −1
γ ±
a H2O
γ ±
a H2O
NaTcO 4
HTcO 4
0.1
0.7455
0.99669
0.7681
0.99666
0.2
0.6937
0.99348
0.7239
0.99338
0.3
0.6605
0.99034
0.7009
0.99009
0.4
0.6350
0.98726
0.6871
0.98677
0.5
0.6141
0.98424
0.6785
0.98342
0.6
0.5963
0.98127
0.6733
0.98004
0.7
0.5808
0.97835
0.6704
0.97661
0.8
0.5672
0.97545
0.6694
0.97314
0.9
0.5552
0.97258
0.6699
0.96961
1.0
0.5444
0.96973
0.6716
0.96604
1.5
0.5050
0.95560
0.6954
0.94726
2.0
0.4809
0.94141
0.7408
0.92661
2.5
0.4656
0.92700
0.8080
0.90365
3.0
0.4559
0.91234
0.9004
0.8780
3.5
0.4499
0.8974
1.024
0.8495
4.0
0.4466
0.8823
1.186
0.8178
4.5
0.4453
0.8669
1.399
0.7832
5.0
0.4458
0.8513
1.678
0.7456
5.5
0.4477
0.8354
6.0
0.4509
0.8193
6.5
0.4551
0.8030
7.0
0.4601
0.7865
7.5
0.4655
0.7701
8.0
0.4708
0.7540
of ion i (in mol·kg
−1 H 2 O).
φ = −
1000 ln(a w )
M w m i
(3.3)
The appropriate binary and mixing Pitzer parameters for Na
+
/Cs
+
/TcO
−
4 /H 2 O
mixtures used by Könnecke et al. (1997) are listed in Table 3.2.
The electrical conductance of TcO
−
4 (25 °C), Λ
0 , is equal to 55.4 ± 0.5 S·cm
2
Eq
−1 (Rard et al. 1999). The conductance of potassium pertechentate solutions at
25 °C was studied in early works of Schwochau and Astheimer (1962). An analysis
of their results performed by Rard et al. (1999) indicates that the following Debye–
Hückel–Onsager limiting law, where I c is the ionic strength in molar units, can be
3 Technetium Coordinated by Inorganic Ligands in Aqueous …
Table 3.1 Mean molar activity coefficients and water activity for NaTcO 4 and HTcO 4 solutions
at 25 °C (Rard and Miller 1991)
Molality/mol·kg −1
γ ±
a H2O
γ ±
a H2O
NaTcO 4
HTcO 4
0.1
0.7455
0.99669
0.7681
0.99666
0.2
0.6937
0.99348
0.7239
0.99338
0.3
0.6605
0.99034
0.7009
0.99009
0.4
0.6350
0.98726
0.6871
0.98677
0.5
0.6141
0.98424
0.6785
0.98342
0.6
0.5963
0.98127
0.6733
0.98004
0.7
0.5808
0.97835
0.6704
0.97661
0.8
0.5672
0.97545
0.6694
0.97314
0.9
0.5552
0.97258
0.6699
0.96961
1.0
0.5444
0.96973
0.6716
0.96604
1.5
0.5050
0.95560
0.6954
0.94726
2.0
0.4809
0.94141
0.7408
0.92661
2.5
0.4656
0.92700
0.8080
0.90365
3.0
0.4559
0.91234
0.9004
0.8780
3.5
0.4499
0.8974
1.024
0.8495
4.0
0.4466
0.8823
1.186
0.8178
4.5
0.4453
0.8669
1.399
0.7832
5.0
0.4458
0.8513
1.678
0.7456
5.5
0.4477
0.8354
6.0
0.4509
0.8193
6.5
0.4551
0.8030
7.0
0.4601
0.7865
7.5
0.4655
0.7701
8.0
0.4708
0.7540
of ion i (in mol·kg
−1 H 2 O).
φ = −
1000 ln(a w )
M w m i
(3.3)
The appropriate binary and mixing Pitzer parameters for Na
+
/Cs
+
/TcO
−
4 /H 2 O
mixtures used by Könnecke et al. (1997) are listed in Table 3.2.
The electrical conductance of TcO
−
4 (25 °C), Λ
0 , is equal to 55.4 ± 0.5 S·cm
2
Eq
−1 (Rard et al. 1999). The conductance of potassium pertechentate solutions at
25 °C was studied in early works of Schwochau and Astheimer (1962). An analysis
of their results performed by Rard et al. (1999) indicates that the following Debye–
Hückel–Onsager limiting law, where I c is the ionic strength in molar units, can be