Chemistry:Hydrolysis constant

From HandWiki

The word hydrolysis is applied to chemical reactions in which a substance reacts with water. In organic chemistry, the products of the reaction are usually molecular, being formed by combination with H and OH groups (e.g., hydrolysis of an ester to an alcohol and a carboxylic acid). In inorganic chemistry, the word most often applies to cations forming soluble hydroxide or oxide complexes with, in some cases, the formation of hydroxide and oxide precipitates.

Metal hydrolysis and associated equilibrium constant values

The hydrolysis reaction for a hydrated metal ion in aqueous solution can be written as:

p Mz+ + q H2O ⇌ Mp(OH)q(pz–q) + q H+

and the corresponding formation constant as:

[math]\displaystyle{ \beta_{pq} = \frac{[M_p(OH)_q^{(pz-q)}][H^+]^q}{[M^{z+}]^p} }[/math]

and associated equilibria can be written as:

MOx(OH)z–2x(s) + z H+ ⇌ Mz+ + (z–x) H2O
MOx(OH)z–2x(s) + x H2O ⇌ Mz+ + z OH
p MOx(OH)z–2x(s) + (pz–q) H+ ⇌ Mp(OH)q(pz–q) + (pz–px–q) H2O

Aluminium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[1] Brown and Ekberg, 2016[2] Hummel and Thoenen, 2023[3]
Al3+ + H2O ⇌ AlOH2+ + H+ –4.97 −4.98 ± 0.02 −4.98 ± 0.02
Al3+ + 2 H2O ⇌ Al(OH)2+ + 2 H+ –9.3 −10.63 ± 0.09 −10.63 ± 0.09
Al3+ + 3 H2O ⇌ Al(OH)3 + 3 H+ –15.0 −15.66 ± 0.23 −15.99 ± 0.23
Al3+ + 4 H2O ⇌ Al(OH)4 + 4 H+ –23.0 −22.91 ± 0.10 −22.91 ± 0.10
2 Al3+ + 2 H2O ⇌ Al2(OH)24+ + 2 H+ –7.7 −7.62 ± 0.11 −7.62 ± 0.11
3 Al3+ + 4 H2O ⇌ Al3(OH)45+ + 4 H+ –13.94 −14.06 ± 0.22 −13.90 ± 0.12
13 Al3+ + 28 H2O ⇌ Al13O4(OH)247+ + 32 H+ –98.73 −100.03 ± 0.09 −100.03 ± 0.09
α-Al(OH)3(s) + 3 H+ ⇌ Al3+ + 3 H2O 8.5 7.75 ± 0.08 7.75 ± 0.08
γ-AlOOH(s) + 3 H+ ⇌ Al3+ + 3 H2O 7.69 ± 0.15 9.4 ± 0.4

Americium(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction NIST46[4] Brown and Ekberg, 2016[5] Grenthe et al, 2020[6]
Am3+ + H2O ⇌ Am(OH)2+ + H+ –6.5 ± 0.1 –7.22 ± 0.03 –7.2 ± 0.5
Am3+ + 2 H2O ⇌ Am(OH)2+ + 2 H+ –14.1 ± 0.3 –14.9 ± 0.2 –15.1 ± 0.7
Am3+ + 3 H2O ⇌ Am(OH)3 + 3 H+ –25.7 –26.0 ± 0.2 –26.2 ± 0.5
Am3+ + 3 H2O ⇌ Am(OH)3(am) + 3 H+ –16.9 ± 0.1 –16.9 ± 0.8 –16.9 ± 0.8
Am3+ + 3 H2O ⇌ Am(OH)3(cr) + 3 H+ –15.2 –15.62 ± 0.04 –15.6 ± 0.6

Americium(V)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Brown and Ekberg, 2016[7] Grenthe et al, 2020[6]
AmO2+ + H2O ⇌ AmO2(OH) + H+ –10.7 ± 0.2
AmO2+ + 2 H2O ⇌ AmO2(OH)2 + 2 H+ –22.9 ± 0.7
AmO2+ + H2O ⇌ AmO2(OH)(am) + H+ –5.4 ± 0.4 –5.3 ± 0.5

Antimony(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[8] Lothenbach et al., 1999;[9]

Kitamura et al., 2010[10]

Filella and May, 2003[11]
Sb(OH)3 + H+ ⇌ Sb(OH)2+ + H2O 1.41 1.30 1.371
Sb(OH)3 + H2O ⇌ Sb(OH)4 + H+ ‒11.82 ‒11.93 ‒11.70
0.5 Sb2O3(s) + 1.5 H2O ⇌ Sb(OH)3 ‒4.24
Sb2O3(rhombic,s) + 3 H2O ⇌ 2 Sb(OH)3 ‒8.72 ‒10.00
Sb2O3(cubic,s) + 3 H2O ⇌ 2 Sb(OH)3 ‒11.40

Antimony(V)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[8] Lothenbach et al., 1999;[9] Kitamura et al., 2010[10]
Sb(OH)5 + H2O ⇌ Sb(OH)6 + H+ ‒2.72 ‒2.72
12 Sb(OH)5 + 4 H2O ⇌ Sb12(OH)644‒ + 4 H+ 20.34 20.34
12 Sb(OH)5 + 5 H2O ⇌ Sb12(OH)655‒ + 5 H+ 16.72 16.72
12 Sb(OH)5 + 6 H2O ⇌ Sb12(OH)666‒ + 6 H+ 11.89 11.89
12 Sb(OH)5 + 7 H2O ⇌ Sb12(OH)677‒ + 7 H+ 6.07 6.07
0.5 Sb2O5(s) + 2.5 H2O ⇌ Sb(OH)5 ‒3.7
Sb2O5(am) + 5 H2O ⇌ 2 Sb(OH)5 ‒7.400

Arsenic(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[12] Nordstrom and Archer, 2003[13] Nordstrom et al., 2014[14]
As(OH)4 + H+ ⇌ As(OH)3 + H2O 9.29 9.17 9.24 ± 0.02

Arsenic(V)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer[12] Khodakovsky et al. (1968)[15] Nordstrom and Archer, 2003[13] Nordstrom et al., 2014[14]
H2AsO4 + H+ ⇌ H3AsO4 2.24 2.21 2.26 ± 0.078 2.25 ± 0.04
HAsO42‒ + H+ ⇌ H2AsO4 6.93 6.99 ± 0.1 6.98 ± 0.11
AsO43‒ + H+ ⇌ HAsO42‒ 11.51 11.80 ± 0.1 11.58 ± 0.05
HAsO42‒ + 2 H+ ⇌H3AsO4 9.20
AsO43‒ + 3 H+ ⇌ H3AsO4 20.70

Barium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[16] Nordstrom et al., 1990[17] Brown and Ekberg, 2016[18]
Ba2+ + H2O ⇌ BaOH+ + H+ –13.47 –13.47 –13.32 ± 0.07

Berkelium(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Brown and Ekberg, 2016[19]
Bk3+ + 3 H2O ⇌ Bk(OH)3(s) + 3 H+ –13.5 ± 1.0

Beryllium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[20]
Be2+ + H2O ⇌ BeOH+ + H+ –5.10
Be2+ + 2 H2O ⇌ Be(OH)2 + 2 H+ –23.65
Be2+ + 3 H2O ⇌ Be(OH)3 + 3 H+ –23.25
Be2+ + 4 H2O ⇌ Be(OH)42– + 4 H+ –37.42
2 Be2+ + H2O ⇌ Be2OH3+ + H+ –3.97
3 Be2+ + 3 H2O ⇌ Be3(OH)33+ + 3 H+ –8.92
6 Be2+ + 8 H2O ⇌ Be6(OH)84+ + 8 H+ –27.2
α-Be(OH)2(cr) + 2 H+ ⇌ Be2+ + 2 H2O 6.69

Bismuth

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[21] Lothenbach et

al., 1999[9]

NIST46[4] Kitamura et

al., 2010[10]

Brown and

Ekberg, 2016[22]

Bi3+ + H2O ⇌ BiOH2+ + H+ –1.0 –0.92 –1.1 –0.920 –0.92 ± 0.15
Bi3+ + 2 H2O ⇌ Bi(OH)2+ + 2 H+ (–4) –2.56 –4.5 –2.560 ± 1.000 –2.59 ± 0.26
Bi3+ + 3 H2O ⇌ Bi(OH)3 + 3 H+ –8.86 –5.31 –9.0 –8.940 ± 0.500 –8.78 ± 0.20
Bi3+ + 4 H2O ⇌ Bi(OH)4 + 4 H+ –21.8 –18.71 –21.2 –21.660 ± 0.870 –22.06 ± 0.14
3 Bi3+ + 4 H2O ⇌ Bi3(OH)45+ + 4 H+ –0.80 –0.800
6 Bi3+ + 12 H2O ⇌ Bi6(OH)126+ + 12 H+ 1.34 1.340 0.98 ± 0.13
9 Bi3+ + 20 H2O = Bi9(OH)207+ + 20 H+ –1.36 –1.360
9 Bi3+ + 21 H2O = Bi9(OH)216+ + 21 H+ –3.25 –3.250
9 Bi3+ + 22 H2O = Bi9(OH)225+ + 22 H+ –4.86 –4.860
Bi(OH)3(am) + 3 H+ = Bi3+ + 3 H2O 31.501 ± 0.927
α-Bi2O3(cr) + 6 H+ = 2 Bi3+ + 3 H2O 0.76
BiO1.5(s, α) + 3 H+ = Bi3+ + 1.5 H2O 3.46 31.501 ± 0.927 2.88 ± 0.64

Boron

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[23] NIST46[4]
B(OH)3 + H2O ⇌ Be(OH)4+ + H+ –9.236 –9.236 ± 0.002
2 B(OH)3 ⇌ B2(OH)5 + H+ –9.36 –9.306
3 B(OH)3 ⇌ B3O3(OH)4 + H+ + 2 H2O –7.03 –7.306
4 B(OH)3 ⇌ B4O5(OH)42– + 2 H+ + 3 H2O –16.3 –15.032

Cadmium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[24] Powell et al., 2011[25] Brown and Ekberg, 2016[26]
Cd2+ + H2O ⇌ CdOH+ + H+ −10.08 –9.80 ± 0.10 −9.81 ± 0.10
Cd2+ + 2 H2O ⇌ Cd(OH)2 + 2 H+ –20.35 –20.19 ± 0.13 −20.6 ± 0.4
Cd2+ + 3 H2O ⇌ Cd(OH)3 + 3 H+ <–33.3 –33.5 ± 0.5 −33.5 ± 0.5
Cd2+ + 4 H2O ⇌ Cd(OH)42– + 4 H+ –47.35 –47.28 ± 0.15 −47.25 ± 0.15
2 Cd2+ + H2O ⇌ Cd2OH3+ + H+ –9.390 –8.73 ± 0.01 −8.74 ± 0.10
4 Cd2+ + 4 H2O ⇌ Cd4(OH)44+ + H+ –32.85
Cd(OH)2(s) ⇌ Cd2+ + 2 OH –14.28 ± 0.12
Cd(OH)2(s) + 2 H+ ⇌ Cd2+ + 2 H2O 13.65 13.72 ± 0.12 13.71 ± 0.12

Calcium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[16] Nordstrom et al., 1990[17] Brown and Ekberg, 2016[27]
Ca2+ + H2O ⇌ CaOH+ + H+ –12.85 –12.78 –12.57 ± 0.03
Ca(OH)2(cr) + 2 H+ ⇌ Ca2+ + 2 H2O 22.80 22.8 22.75 ± 0.02

Californium(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Brown and Ekberg, 2016[19]
Cf3+ + 3 H2O ⇌ Bk(OH)3(s) + 3 H+ –13.0 ± 1.0

Cerium(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[28] NIST46[4] Brown and Ekberg, 2016[29]
Ce3+ + H2O ⇌ CeOH2+ + H+ –8.3 –8.3 –8.31 ± 0.03
2 Ce3+ + 2 H2O ⇌ Ce2(OH)24+ + 2 H+ –16.0 ± 0.2
3 Ce3+ + 5 H2O ⇌ Ce3(OH)54+ + 5 H+ –34.6 ± 0.3
Ce(OH)3(s) + 3 H+ ⇌ Ce3+ + 3 H2O 18.5 ± 0.5
Ce(OH)3(s) ⇌ Ce3+ + 3 OH –22.1 ± 0.9

Chromium(II)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K (The divalent state is unstable in water, producing hydrogen whilst being oxidised to a higher valency state (Baes and Mesmer, 1976). The reliability of the data is in doubt.):

Reaction NIST46[4] Ball and Nordstrom, 1988[30]
Cr2+ + H2O ⇌ CrOH+ + H+ –5.5
Cr(OH)2(s) ⇌ Cr2+ + 2 OH –17 ± 0.02

Chromium(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[31] Rai et al., 1987[32] Ball and Nordstrom, 1988[30] Brown and Ekberg, 2016[33]
Cr3+ + H2O ⇌ CrOH2+ + H+ –4.0 –3.57 ± 0.08 –3.60 ± 0.07
Cr3+ + 2 H2O ⇌ Cr(OH)2+ + 2 H+ –9.7 –9.84 –9.65 ± 0.20
Cr3+ + 3 H2O ⇌ Cr(OH)3 + 3 H+ –18 –16.19 –16.25 ± 0.19
Cr3+ + 4 H2O ⇌ Cr(OH)4- + 4 H+ –27.4 –27.65 ± 0.12 –27.56 ± 0.21
2 Cr3+ + 2 H2O ⇌ Cr2(OH)24+ + 2 H+ –5.06 –5.0 –5.29 ± 0.16
3 Cr3+ + 4 H2O ⇌ Cr3(OH)45+ + 4 H+ –8.15 –10.75 ± 0.15 –9.10 ± 0.14
Cr(OH)3(s) + 3 H+ ⇌ Cr3+ + 3 H2O 12 9.35 9.41 ± 0.17
Cr2O3(s) + 6 H+ ⇌ 2 Cr3+ + 3 H2O 8.52
CrO1.5(s) + 3 H+ ⇌ Cr3+ + 1.5 H2O 7.83 ± 0.10

Chromium(VI)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[34] Ball and Nordstrom, 1998[30]
CrO42– + H+ ⇌ HCrO4 6.51 6.55 ± 0.04
HCrO4 + H+ ⇌ H2CrO4 –0.20
CrO42– + 2 H+ ⇌ H2CrO4 6.31
2 HCrO4 ⇌ Cr2O72– + H2O 1.523
2 CrO42– + 2 H+ ⇌ Cr2O72– + H2O 14.7 ± 0.1

Cobalt(II)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[35] Brown and Ekberg, 2016[36]
Co2+ + H2O ⇌ CoOH+ + H+ –9.65 −9.61 ± 0.17
Co2+ + 2 H2O ⇌ Co(OH)2 + 2 H+ –18.8 −19.77 ± 0.11
Co2+ + 3 H2O ⇌ Co(OH)3 + 3 H+ –31.5 −32.01 ± 0.33
Co2+ + 4 H2O ⇌ Co(OH)42– + 4 H+ –46.3
2 Co2+ + H2O ⇌ Co2(OH)3+ + H+ –11.2
4 Co2+ + 4 H2O ⇌ Co4(OH)44+ + 4H+ –30.53
Co(OH)2(s) + 2 H+ ⇌ Co2+ + 2 H2O 12.3 13.24 ± 0.12
CoO(s) + 2 H+ ⇌ Co2+ + H2O 13.71 ± 0.10

Cobalt(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Brown and Ekberg, 2016[37]
Co3+ + H2O ⇌ CoOH2+ + H+ −1.07 ± 0.11

Copper(I)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Brown and Ekberg, 2016[38]
Cu+ + H2O ⇌ CuOH + H+ –7.8 ± 0.4
Cu+ + 2 H2O ⇌ Cu(OH)2 + 2 H+ –18.6 ± 0.6

Copper(II)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[39] NIST46[4] Plyasunova et al., 1997[40] Powell et al., 2007[41] Brown and Ekberg, 2016[38]
Cu2+ + H2O ⇌ CuOH+ + H+ < –8 –7.7 –7.97 ± 0.09 –7.95 ± 0.16 –7.64 ± 0.17
Cu2+ + 2 H2O ⇌ Cu(OH)2 + 2 H+ (< –17.3) –17.3 –16.23 ± 0.15 –16.2 ± 0.2 –16.24 ± 0.03
Cu2+ + 3 H2O ⇌ Cu(OH)3 + 3 H+ (< –27.8) –27.8 –26.63 ± 0.40 –26.60 ± 0.09 –26.65 ± 0.13
Cu2+ + 4 H2O ⇌ Cu(OH)42– + 4 H+ –39.6 –39.6 –39.73 ± 0.17 –39.74 ± 0.18 –39.70 ± 0.19
2 Cu2+ + H2O ⇌ Cu2(OH)3+ + H+ –6.71 ± 0.30 –6.40 ± 0.12 –6.41 ± 0.17
2 Cu2+ + 2 H2O ⇌ Cu2(OH)22+ + 2 H+ –10.36 –10.3 –10.55 ± 0.17 –10.43 ± 0.07 –10.55 ± 0.02
3 Cu2+ + 4 H2O ⇌ Cu3(OH)42+ + 4 H+ –20.95 ± 0.30 –21.1 ± 0.2 –21.2 ± 0.4
CuO(s) + 2 H+ ⇌ Cu2+ + H2O 7.62 7.64 ± 0.06 7.64 ± 0.06 7.63 ± 0.05
Cu(OH)2(s) + 2 H+ ⇌ Cu2+ + 2 H2O 8.67 ± 0.05 8.68 ± 0.10

Curium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Brown and Ekberg, 2016[42]
Cm3+ + H2O ⇌ Cm(OH)2+ + H+ −7.66 ± 0.07
Cm3+ + 2 H2O ⇌ Cm(OH)2+ + 2 H+ −15.9 ± 0.1
Cm3+ + 3 H2O ⇌ Cm(OH)3(s) + 3 H+ −13.9 ± 0.4

Dysprosium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[28] Brown and Ekberg, 2016[43]
Dy3+ + H2O ⇌ DyOH2+ + H+ −8.0 −7.53 ± 0.14
Dy3+ + 2 H2O ⇌ Dy(OH)2+ + 2 H+ (–16.2)
Dy3+ + 3 H2O ⇌ Dy(OH)3 + 3 H+ (–24.7)
Dy3+ + 4 H2O ⇌ Dy(OH)4 + 4 H+ –33.5
2 Dy3+ + 2 H2O ⇌ Dy2(OH)24+ + 2 H+ −13.76 ± 0.20
3 Dy3+ + 5 H2O ⇌ Dy3(OH)54+ + 5 H+ −30.6 ± 0.3
Dy(OH)3(s) + 3 H+ ⇌ Dy3+ + 3 H2O 15.9 16.26 ± 0.30
Dy(OH)3(c) + OH ⇌ Dy(OH)4 −3.6
Dy(OH)3(c) ⇌ Dy(OH)3 −8.8

Erbium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[28] Brown and Ekberg, 2016[44]
Er3+ + H2O ⇌ ErOH2+ + H+ −7.9 −7.46 ± 0.09
Er3+ + 2 H2O ⇌ Er(OH)2+ + 2 H+ (−15.9)
Er3+ + 3 H2O ⇌ Er(OH)3 + 3 H+ (−24.2)
Er3+ + 4 H2O ⇌ Er(OH)4 + 4 H+ −32.6
2 Er3+ + 2 H2O ⇌ Er2(OH)24+ + 2 H+ −13.65 −13.50 ± 0.20
3 Er3+ + 5 H2O ⇌ Er3(OH)54+ + 5 H+ <−29.3 −31.0 ± 0.3
Er(OH)3(s) + 3 H+ ⇌ Er3+ + 3 H2O 15.0 15.79 ± 0.30
Er(OH)3(c) + OH ⇌ Er(OH)4 −3.6
Er(OH)3(c) ⇌ Er(OH)3 ~ −9.2

Europium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[28] NIST46[4] Hummel et al., 2002[45] Brown and Ekberg, 2016[29]
Eu3+ + H2O ⇌ EuOH2+ + H+ –7.8 –7.64 ± 0.04 –7.66 ± 0.05
Eu3+ + 2 H2O ⇌ Eu(OH)2+ + 2 H+ –15.1 ± 0.2
Eu3+ + 3 H2O ⇌ Eu(OH)3 + 3 H+ –23.7 ± 0.1
Eu3+ + 4 H2O ⇌ Eu(OH)4 + 4 H+ –36.2 ± 0.5
2 Eu3+ + 2 H2O ⇌ Eu2(OH)24+ + 2 H+ - –14.1 ± 0.2
3 Eu3+ + 5 H2O ⇌ Eu3(OH)54+ + 5 H+ - –32.0 ± 0.3
Eu(OH)3(s) + 3 H+ ⇌ Eu3+ + 3 H2O 17.5 17.6 ± 0.8 (am)

14.9 ± 0.3 (cr)

16.48 ± 0.30
Eu(OH)3(s) ⇌ Eu3+ + 3 OH –24.5 ± 0.7 (am)

–26.5 (cr)

Gadolinium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[46] Brown and Ekberg, 2016[47]
Gd3+ + H2O ⇌ GdOH2+ + H+ –8.0 –7.87 ± 0.05
Gd3+ + 2 H2O ⇌ Gd(OH)2+ + 2 H+ (–16.4)
Gd3+ + 3 H2O ⇌ Gd(OH)3 + 3 H+ (–25.2)
Gd3+ + 4 H2O ⇌ Gd(OH)4 + 4 H+ –34.4
2 Gd3+ + 2 H2O ⇌ Gd2(OH)24+ + 2 H+ –14.16 ± 0.20
3 Gd3+ + 5 H2O ⇌ Gd3(OH)54+ + 5 H+ –33.0 ± 0.3
Gd(OH)3(s) + 3 H+ ⇌ Gd3+ + 3 H2O 15.6 17.20 ± 0.48
Gd(OH)3(c) + OH ⇌ Gd(OH)4 –4.8
Gd(OH)3(c) ⇌ Gd(OH)3 –9.6

Gallium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[48] Smith et al., 2003[49] Brown and Ekberg, 2016[50]
Ga3+ + H2O ⇌ GaOH2+ + H+ –2.6 –2.897 –2.74
Ga3+ + 2 H2O ⇌ Ga(OH)2+ + 2 H+ –5.9 –6.694 –7.0
Ga3+ + 3 H2O ⇌ Ga(OH)3 + 3 H+ –10.3 –11.96
Ga3+ + 4 H2O ⇌ Ga(OH)4 + 4 H+ –16.6 –16.588 –15.52
Ga(OH)3(s) ⇌ Ga3+ + 3 OH [math]\displaystyle{ \approx }[/math]–37 –37.0
GaO(OH)(s) + H2O ⇌ Ga3+ + 3 OH –39.06 –39.1 –40.51

Germanium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[51] Wood and Samson, 2006[52] Filella and May, 2023[53]
Ge(OH)4 ⇌ GeO(OH)3- + H+ –9.31 –9.32 ± 0.05 –9.099
Ge(OH)4 ⇌ GeO2(OH)22+ + 2 H+ –21.9
GeO2(OH)22– + H+ ⇌ GeO(OH)3 12.76
8 Ge(OH)4 ⇌ Ge8O16(OH)33- + 13 H2O + 3 H+ –14.24
8 Ge(OH)4 + 3 OH ⇌ Ge8(OH)353– 28.33
GeO2(s, hexa) + 2 H2O ⇌ Ge(OH)4 –1.35 –1.373
GeO2(s, tetra) + 2 H2O ⇌ Ge(OH)4 -4.37 –5.02 –4.999

Gold(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[54]
Au(OH)3 +2 H+ ⇌ AuOH2+ + 2 H2O 1.51
Au(OH)3 + H+ ⇌ Au(OH)2+ + H2O < 1.0
Au(OH)3 + H2O ⇌ Au(OH)4 + H+ –11.77
Au(OH)3 + 2 H2O ⇌ Au(OH)52– + 2 H+ –25.13
Au(OH)52– + 3 H2O ⇌ Au(OH)63– + 3 H+ < –41.1
Au(OH)3(c) ⇌ Au(OH)3 –5.51

Hafnium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[55] Brown and Ekberg, 2016[56]
Hf4+ + H2O ⇌ HfOH3+ + H+ –0.25 −0.26 ± 0.10
Hf4+ + 2 H2O ⇌ Hf(OH)22+ + 2 H+ (–2.4)
Hf4+ + 3 H2O ⇌ Hf(OH)3+ + 3 H+ (–6.0)
Hf4+ + 4 H2O ⇌ Hf(OH)4 + 4 H+ –10.7* −3.75 ± 0.34*
Hf4+ + 5 H2O ⇌ Hf(OH)5 + 5 H+ –17.2
3 Hf4+ + 4 H2O ⇌ Hf3(OH)48+ + 4 H+ 0.55 ± 0.30
4 Hf4+ + 8 H2O ⇌ Hf4(OH)88+ + 8 H+ 6.00 ± 0.30
HfO2(s) + 4 H+ ⇌ Hf4+ + 2 H2O –1.2* –5.56 ± 0.15*
HfO2(am) + 4 H+ ⇌ Hf4+ + 2 H2O –3.11 ± 0.20

*Errors in compilations concerning equilibrium and/or data elaboration. Data not recommended. Strongly suggested to refer to the original papers.

Holmium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[28] Brown and Ekberg, 2016[57]
Ho3+ + H2O ⇌ HoOH2+ + H+ −8.0 −7.43 ± 0.05
2 Ho3+ + 2 H2O ⇌ Ho2(OH)24+ + 2 H+ −13.5 ± 0.2
3 Ho3+ + 5 H2O ⇌ Ho3(OH)54+ + 5 H+ −30.9 ± 0.3
Ho(OH)3(s) + 3 H+ ⇌ Ho3+ + 3 H2O 15.4 15.60 ± 0.30

Indium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[58] NIST46[4] Brown and Ekberg, 2016[59]
In3+ + H2O ⇌ InOH2+ + H+ –4.00 –3.927 –3.96
In3+ + 2 H2O ⇌ In(OH)2+ + 2 H+ –7.82 –7.794 –9.16
In3+ + 3 H2O ⇌ In(OH)3 + 3 H+ –12.4 –12.391
In3+ + 4 H2O ⇌ In(OH)4 + 4 H+ –22.07 –22.088 –22.05
In(OH)3(s) ⇌ In3+ + 3 OH –36.92 –36.9 –36.92
1/2 In2O3(s) + 3/2 H2O ⇌ In3+ + 3 OH –35.24

Iridium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Brown and Ekberg, 2016[60]
Ir3+ + H2O ⇌ IrOH2+ + H+ ‒3.77 ± 0.10
Ir3+ + 2 H2O ⇌ Ir(OH)2+ + 2 H+ ‒8.46 ± 0.20
Ir(OH)3(s) + 3 H+ ⇌ Ir3+ + 3 H2O 8.88 ± 0.20

Iron(II)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[61] Nordstrom et al., 1990[17] Hummel et al., 2002[45] Lemire et al., 2013[62] Brown and Ekberg, 2016[63]
Fe2+ + H2O ⇌ FeOH+ + H+ –9.3 –9.5 –9.5 –9.1 ± 0.4 −9.43 ± 0.10
Fe2+ + 2 H2O ⇌ Fe(OH)2 + 2 H+ –20.5 −20.52 ± 0.08
Fe2+ + 3 H2O ⇌ Fe(OH)3- + 3 H+ –29.4 −32.68 ± 0.15
Fe(OH)2(s) +2 H+ ⇌ Fe2+ + 2 H2O 12.27 ± 0.88

Iron(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[61] Lemire et al., 2013[62] Brown and Ekberg, 2016[64]
Fe3+ + H2O ⇌ FeOH2+ + H+ –2.19 −2.15 ± 0.07 –2.20 ± 0.02
Fe3+ + 2 H2O ⇌ Fe(OH)2+ + 2 H+ –5.67 −4.8 ± 0.4 –5.71 ± 0.10
Fe3+ + 3 H2O ⇌ Fe(OH)3 + 3 H+ <–12 <–14 –12.42 ± 0.20
Fe3+ + 4 H2O ⇌ Fe(OH)4 + 4 H+ –21.6 −21.5 ± 0.5 –21.60 ± 0.23
2 Fe3+ + 2 H2O ⇌ Fe2(OH)24+ + 2 H+ –2.95 –2.91 ± 0.07 –2.91 ± 0.07
3 Fe3+ + 4 H2O ⇌ Fe3(OH)45+ + 4 H+ –6.3 −6.3 ± 0.1
Fe(OH)3(s) +3 H+ ⇌ Fe3+ + 3 H2O

2-line ferrihydrite

2.5 3.5 3.50 ± 0.20
Fe(OH)3(s) ⇌ Fe3+ + 3 OH

6-line ferrihydrite

−38.97 ± 0.64
α-FeOOH(s)+ 3 H+ ⇌ Fe3+ + 2 H2O

goethite

0.5 0.33 ± 0.10
α-FeOOH + H2O ⇌ Fe3+ + 3 OH

goethite

−41.83 ± 0.37
0.5 α-Fe2O3(s)+ 3 H+ ⇌ Fe3+ + 1.5 H2O

hematite

0.36 ± 0.40
0.5 α-Fe2O3 + 1.5 H2O ⇌ Fe3+ + 3 OH

hematite

−42.05 ± 0.26
0.5 γ-Fe2O3(s) + 3 H+ ⇌ Fe3+ + 1.5 H2O

maghemite

1.61 ± 0.61
0.5 γ-Fe2O3 + 1.5 H2O ⇌ Fe3+ + 3 OH

maghemite

−40.59 ± 0.29
α-FeOOH(s)+ 3 H+ ⇌ Fe3+ + 2 H2O

lepidocrocite

1.85 ± 0.37
γ-FeOOH + H2O ⇌ Fe3+ + 3 OH

lepidocrocite

−40.13 ± 0.37
Fe(OH)3(s) + 3 H+ ⇌ Fe3+ + 3 H2O

magnetite

−12.26 ± 0.26

Lanthanum

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[65] Brown and Ekberg, 2016[66]
La3+ + H2O ⇌ LaOH2+ + H+ –8.5 –8.89 ± 0.10
2 La3+ + 2 H2O ⇌ La2(OH)24+ + 2 H+ ≤ –17.5 –17.57 ± 0.20
3 La3+ + 5 H2O ⇌ La3(OH)54+ + 5 H+ ≤ –38.3 –37.8 ± 0.3
5 La3+ + 9 H2O ⇌ La5(OH)96+ + 9 H+ –71.2
La(OH)3(s) + 3 H+ ⇌ La3+ + 3 H2O 20.3 19.72 ± 0.34

Lead(II)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[67] NIST46[4] Powell et al, 2009[68] Brown and Ekberg, 2016[69] Cataldo et al., 2018[70]
Pb2+ + H2O ⇌ PbOH+ + H+ –7.71 –7.6 –7.46 ± 0.06 –7.49 ± 0.13 –6.47± 0.03
Pb2+ + 2 H2O ⇌ Pb(OH)2 + 2 H+ –17.12 –17.1 –16.94 ± 0.09 –16.99 ± 0.06 –16.12 ± 0.01
Pb2+ + 3 H2O ⇌ Pb(OH)3- + 3 H+ –28.06 –28.1 –28.03± 0.06 –27.94 ± 0.21 –28.4 ± 0.1
Pb2+ + 4 H2O ⇌ Pb(OH)42- + 4 H+ –40.8
2 Pb2+ + H2O ⇌ Pb2(OH)3+ + H+ –6.36 –6.4 –7.28± 0.09 –6.73 ± 0.31
3 Pb2+ + 4 H2O ⇌ Pb3(OH)42+ + 4 H+ –23.88 –23.9 –23.01 ± 0.07 –23.43 ± 0.10
3 Pb2+ + 5 H2O ⇌ Pb3(OH)5+ + 5 H+ –31.11 ± 0.10
4 Pb2+ + 4 H2O ⇌ Pb4(OH)44+ + 4 H+ –20.88 –20.9 –20.57± 0.06 –20.71 ± 0.18
6 Pb2+ + 8 H2O ⇌ Pb6(OH)84+ + 8 H+ –43.61 –43.6 –42.89± 0.07 –43.27 ± 0.47
PbO(s) + 2 H+ ⇌ Pb2+ + H2O 12.62 (red)

12.90 (yellow)

PbO(s) +H2O ⇌ Pb2+ + 2 OH –15.28 (red) -15.3 –15.3 (red)

–15.1 (yellow)

–15.37 ± 0.04 (red)

–15.1 ± 0.08 (yellow)

Pb2O(OH)2(s) +H2O ⇌ 2 Pb2+ + 4 OH –14.9
PbO(s) +H2O ⇌ Pb(OH)2 –4.4 (red)

–4.2 (yellow)

Pb2O(OH)2(s) +H2O ⇌ 2 Pb(OH)2 –4.0
PbO(s) + 2 H2O ⇌ Pb(OH)3 + H+ –1.4 (red)

–1.2 (yellow)

Pb2O(OH)2(s) + 2 H2O ⇌ 2 Pb(OH)3 + 2 H+ –1.0

Lead(IV)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Feitknecht and Schindler, 1963[71]
β-PbO2 + 2 H2O ⇌ Pb4+ + 4 OH –64
β-PbO2 + 2 H2O + 2 OH ⇌ Pb(OH)62– –4.5

Lithium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[72] Nordstrom et al., 1990[17] Brown and Ekberg, 2016[73]
Li+ + H2O ⇌ LiOH + H+ –13.64 –13.64 –13.84 ± 0.14

Magnesium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[74] Nordstrom et al., 1990[17] Brown and Ekberg, 2016[75]
Mg2+ + H2O ⇌ MgOH+ + H+ –11.44 –11.44 –11.70 ± 0.04
4 Mg2+ + 4 H2O ⇌ Mg4(OH)44+ + 4 H+ –39.71
Mg(OH)2(cr) + 2 H+ ⇌ Mg2+ + 2 H2O 16.84 16.84 17.11 ± 0.04

Manganese(II)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Perrin et al., 1969[76] Baes and Mesmer, 1976[77] Nordstrom et al., 1990[17] Hummel et al., 2002[45] Brown and Ekberg, 2016[78]
Mn2+ + H2O ⇌ MnOH+ + H+ –10.59 –10.59 –10.59 –10.59 −10.58 ± 0.04
Mn2+ + 2 H2O ⇌ Mn(OH)2 + 2 H+ –22.2 −22.18 ± 0.20
Mn2+ + 3 H2O ⇌ Mn(OH)3 + 3 H+ –34.8 −34.34 ± 0.45
Mn2+ + 4 H2O ⇌ Mn(OH)42– + 4 H+ –48.3 −48.28 ± 0.40
2 Mn2+ + H2O ⇌ Mn2OH3+ + H+ –10.56
2 Mn2+ + 3 H2O ⇌ Mn2(OH)3+ + 6 H+ –23.90
Mn(OH)2(s) + 2 H+ ⇌ Mn2+ + 2 H2O 15.2 15.2 15.2 15.19 ± 0.10
MnO(s) + 2 H+ ⇌ Mn2+ + H2O 17.94 ± 0.12

Manganese(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Brown and Ekberg, 2016[79]
Mn3+ + H2O ⇌ MnOH2+ + H+ –11.70 ± 0.04

Mercury(I)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[80] Brown and Ekberg, 2016[81]
Hg22+ + H2O ⇌ Hg2OH+ + H+ −5.0a −4.45 ± 0.10

(a) 0.5 M HClO4

Mercury(II)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[82] Powell et all, 2005[83] Brown and Ekberg, 2016[79]
Hg2+ + H2O ⇌ HgOH+ + H+ −3.40 –3.40 ± 0.08 –3.40 ± 0.08
Hg2+ + 2 H2O ⇌ Hg(OH)2 + 2 H+ -6.17 –5.98 ± 0.06 −5.96 ± 0.07
Hg2+ + 3 H2O ⇌ Hg(OH)3 + 3 H+ –21.1 –21.1 ± 0.3
HgO(s) + 2 H+ ⇌ Hg2+ + H2O 2.56 2.37 ± 0.08 2.37 ± 0.08

Molybdenum(VI)

Hydrolysis constants (log values) in critical compilations at infinite dilution, T = 298.15 K and I = 3 M NaClO4 (a) or 0.1 M Na+ medium, Data at I = 0 are not available (b):

Reaction Baes and Mesmer, 1976[84] Jolivet, 2000[85] NIST46[4] Crea et al., 2017[86]
MoO42– + H+ ⇌ HMoO4 3.89a 4.24 4.47 ± 0.02
MoO42– + 2 H+ ⇌ H2MoO4 7.50a 8.12 ± 0.03
HMoO4 + H+ ⇌ H2MoO4 4.0
Mo7O246– + H+ ⇌ HMo7O245– 4.4
HMo7O245– + H+ ⇌ H2Mo7O244– 3.5
H2Mo7O244– + H+ ⇌ H3Mo7O243– 2.5
7 MoO42-+ 8 H+ ⇌ Mo7O246– + 4 H2O 57.74a 52.99b 51.93 ± 0.04
7 MoO42– + 9 H+ ⇌ Mo7O23(OH)5– + 4 H2O 62.14a 58.90 ± 0.02
7 MoO42– + 10 H+ ⇌ Mo7O22(OH)24– + 4 H2O 65.68a 64.63 ± 0.05
7 MoO42– + 11 H+ ⇌ Mo7O21(OH)33– + 4 H2O 68.21a 68.68 ± 0.06
19 MoO42- + 34 H+ ⇌ Mo19O594– + 17 H2O 196.3a 196a
MoO3(s) + H2O ⇌ MoO42– + 2 H+ –12.06a

Neodymium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[28] NIST46[4] Neck et al., 2009[87] Brown and Ekberg, 2016[29]
Nd3+ + H2O ⇌ NdOH2+ + H+ –8.0 –8.0 –7.4 ± 0.4 –8.13 ± 0.05
Nd3+ + 2 H2O ⇌ Nd(OH)2+ + 2 H+ (–16.9) –15.7 ± 0.7
Nd3+ + 3 H2O ⇌ Nd(OH)3(aq) + 3 H+ (–26.5) –26.2 ± 0.5
Nd3+ + 4 H2O ⇌ Nd(OH)4 + 4 H+ (–37.1) –37.4 –40.7 ± 0.7
2 Nd3+ + 2 H2O ⇌ Nd2(OH)24+ + 2 H+ –13.86 –13.9 –15.56 ± 0.20
3 Nd3+ + 5 H2O ⇌ Nd3(OH)54+ + 5 H+ < –28.5 –34.2 ± 0.3
Nd(OH)3(s) + 3 H+ ⇌ Nd3+ + 3 H2O 18.6 17.2 ± 0.4 17.89 ± 0.09
Nd(OH)3(s) ⇌ Nd3+ + 3 OH –23.2 ± 0.9 –21.5 (act)

–23.1(inact)

Neptunium(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Brown and Ekberg, 2016[88] Grenthe et al, 2020[6]
Np3+ + H2O ⇌ NpOH2+ + H+ -7.3 ± 0.5 –6.8 ± 0.3

Neptunium(IV)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[89] NIST46[4] Brown and Ekberg, 2016[90] Grenthe et al, 2020[6]
Np4+ + H2O ⇌ NpOH3+ + H+ –1.49 –1.5 –1.31 ± 0.05 0.5 ± 0.2
Np4+ + 2 H2O ⇌ Np(OH)22+ + 2 H+ –3.7 ± 0.3 0.3 ± 0.3
Np4+ + 4 H2O ⇌ Np(OH)4 + 4 H+ –10.0 ± 0.9 –8 ± 1
Np4+ + 4 OH- ⇌ NpO2(am, hyd) + 2 H2O 52 54.9 ± 0.4 57.5 ± 0.3 56.7 ± 0.5

Neptunium(V)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[89] Brown and Ekberg, 2016[91] Grenthe et al, 2020[6]
NpO2+ + + H2O ⇌ NpO2(OH) + H+ –8.85 –10.7 ± 0.5 –11.3 ± 0.7
NpO2+ + 2 H2O ⇌ NpO2(OH)2- + 2 H+ –22.8 ± 0.7 –23.6 ± 0.5
NpO2+ + H2O ⇌ NpO2(OH)(am, fresh) + H+ ≤ –4.7 –5.21 ± 0.05 –5.3 ± 0.2
NpO2+ + H2O ⇌ NpO2(OH)(am, aged) + H+ –4.53 ± 0.06 –4.7 ± 0.5

Neptunium(VI)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer,

1976[92]

NIST46[4] Brown and Ekberg,

2016[93]

Grenthe et

al, 2020[6]

NpO22+ + H2O ⇌ NpO2(OH)+ + H+ –5.15 –5.12 –5.1 ± 0.2 –5.1 ± 0.4
NpO22+ + 3 H2O ⇌ NpO2(OH)3- + 3 H+ –21 ± 1
NpO22+ + 4 H2O ⇌ NpO2(OH)42- + 4 H+ –32 ± 1
2 NpO22+ + 2 H2O ⇌ (NpO2)2(OH)22+ + 2 H+ –6.39 –6.39 –6.2 ± 0.2 –6.2 ± 0.2
3 NpO22+ + 5 H2O ⇌ (NpO2)3(OH)5+ + 5 H+ –17.49 –17.49 –17.0 ± 0.2 –17.1 ± 0.2
NpO22+ + 2 H2O ⇌ NpO3.H2O(cr) + 2 H+ ≥-6.6 –5.4 ± 0.4 –5.4 ± 0.4

Nickel(II)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Feitknecht and Schindler, 1963[71] Baes and Messmer, 1976[94] NIST46[4] Gamsjäger et al., 2005[95] Thoenen et al., 2014[96] Brown and Ekberg, 2016[97]
Ni2+ + H2O ⇌ NiOH+ + H+ –9.86 –9.9 –9.54 ± 0.14 –9.54 ± 0.14 –9.90 ± 0.03
Ni2+ + 2 H2O ⇌ Ni(OH)2 + 2 H+ –19 –19 < –18 –21.15 ± 0.0
Ni2+ + 3 H2O ⇌ Ni(OH)3 + 3 H+ –30 –30 –29.2 ± 1.7 –29.2 ± 1.7
Ni2+ + 4 H2O ⇌ Ni(OH)42– + 4 H+ < –44
2 Ni2+ + H2O ⇌ Ni2(OH)3+ + H+ –10.7 –10.6 ± 1.0 –10.6 ± 1.0 –10.6 ± 1.0
4 Ni2+ + 4 H2O ⇌ Ni4(OH)44+ + 4 H+ –27.74 –27.7 –27.52 ± 0.15 –27.52 ± 0.15 –27.9 ± 0.6
β-Ni(OH)2(s) + 2 H+ ⇌ Ni2+ + 2 H2O 10.8 11.02 ± 0.20 10.96 ± 0.20

11.75 ± 0.13 (microcr)

Ni(OH)2(s) ⇌ Ni2+ + 2 OH –17.2 (inactive) –17.2 –16.97± 0.20 (β)

–17.2 ± 1.3 (cr)

Ni(OH)2(s) + OH ⇌ Ni(OH)3 –4.2 (inactive)
NiO(cr) + 2 H+ ⇌ Ni2+ + H2O 12.38 ± 0.06 12.48 ± 0.15

Niobium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[72] Filella and May, 2020[98]
Nb(OH)5 + H+ ⇌ Nb(OH)4+ + H2O ~ –0.6 1.603
Nb(OH)5 + H2O ⇌ Nb(OH)6 + H+ ~ –4.8 –4.951
Nb6O198– + H+ ⇌ HNb6O197– 14.95
HNb6O197– + H+ ⇌ H2Nb6O196– 13.23
H2Nb6O196– + H+ ⇌ H3Nb6O195– 11.73
1/2 Nb2O5(act) + 5/2 H2O ⇌ Nb(OH)5 ~ –7.4
Nb(OH)5(am,s) ⇌ Nb(OH)5 –7.510
Nb2O5(s) + 5 H2O ⇌ 2 Nb(OH)5 –18.31

Osmium(VI)

Hydrolysis constants (log values) in critical compilations at infinite dilution, I = 0.1 M and T = 298.15 K:

Reaction Galbács et al., 1983[99]
OsO2(OH)42– + H+ ⇌ HOsO2(OH)4 10.4
HOsO2(OH)4 + H+ ⇌ H2OsO2(OH)4 8.5

Osmium(VIII)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Galbács et al., 1983[99]
OsO2(OH)3(O-)aq + H+ ⇌ OsO2(OH)4aq 12.2a
OsO2(OH)2(O-)2aq + H+ ⇌ OsO2(OH)3(O-)aq 14.4b

(a) At I = 0.1 M (b) At I = 2.5 M

Palladium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Perrin et al., 1969[100] Hummel et al., 2002[45] Kitamura and Yul, 2010[101] Brown and Ekberg, 2016[102]
Pd2+ + H2O ⇌ PdOH+ + H+ −0.96 −0.65 ± 0.64 −1.16 ± 0.30
Pd2+ + 2 H2O ⇌ Pd(OH)2 + 2 H+ −2.6 −4 ± 1 −3.11 ± 0.63 −3.07 ± 0.16
Pd2+ + 3 H2O ⇌ Pd(OH)3 + 3 H+ −15.5 ± 1 −14.20 ± 0.63
Pd(OH)2(am) + 2 H+ ⇌ Pd2+ + 2 H2O −3.3 ± 1 −3.4 ± 0.2

Plutonium(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[103] NIST46[4] Brown and Ekberg, 2016[104] Grenthe et al, 2020[6]
Pu3+ + H2O ⇌ PuOH2+ + H+ –7.0 –6.9 ± 0.2 –6.9 ± 0.3
Pu3+ + 3 H2O ⇌ Pu(OH)3(cr) + 3 H+ –19.65 –15.8 ± 0.8 –15 ± 1

Plutonium(IV)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[105] NIST46[4] Brown and Ekberg, 2016[106] Grenthe et al, 2020[6]
Pu4+ + H2O ⇌ PuOH 3+ + H+ –0.5 –0.5 –0.7 ± 0.1 0.6 ± 0.2
Pu4+ + 2 H2O ⇌ Pu(OH)22+ + 2 H+ (–2.3) 0.6 ± 0.3
Pu4+ + 3 H2O ⇌ Pu(OH)3+ + 3 H+ (–5.3) –2.3 ± 0.4
Pu4+ + 4 H2O ⇌ Pu(OH)4 + 4 H+ –9.5 –12.5 ± 0.7 –8.5 ± 0.5
Pu4+ + 4 OH- ⇌ PuO2(am, hyd) + 2 H2O 49.5 47.9 ± 0.4 (0w)

53.8 ± 0.5 (1w)

58.3 ± 0.5

Plutonium(V)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[107] NIST46[4] Brown and Ekberg, 2016[108] Grenthe et al, 2020[6]
PuO2+ + H2O ⇌ PuO2(OH) + H+ –1.49 –1.5 –1.31 ± 0.05 0.5 ± 0.2
PuO2+ + H2O ⇌ PuO2(OH)(am) + H+ –3.7 ± 0.3 0.3 ± 0.3

Plutonium(VI)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer,

1976[109]

NIST46[4] Brown and Ekberg,

2016[110]

Grenthe et

al, 2020[6]

PuO22+ + H2O ⇌ PuO2(OH)+ + H+ –5.6 –5.6 –5.36 ± 0.09 –5.5 ± 0.5
PuO22+ + 2 H2O ⇌ PuO2(OH)2 + 2 H+ –12.9 ± 0.2 –13 ± 1
PuO22+ + 3 H2O ⇌ PuO2(OH)3- + 3 H+ –24 ± 1
2 PuO22+ + 2 H2O ⇌ (PuO2)2(OH)22+ + 2 H+ –8.36 –8.36 –7.8 ± 0.5 –7 ± 1
3 PuO22+ + 5 H2O ⇌ (PuO2)3(OH)5+ + 5 H+ –21.65 –21.65
PuO22+ + 2 OH- ⇌ PuO2(OH)2(am, hyd) 22.8 ± 0.6

Potassium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[72] Nordstrom et al., 1990[17] Brown and Ekberg, 2016[111]
K+ + H2O ⇌ KOH + H+ –14.46 –14.46 –14.5 ± 0.4

Praseodymium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[28] NIST46[4] Brown and Ekberg, 2016[29]
Pr3+ + H2O ⇌ PrOH2+ + H+ –8.1 –8.30 ± 0.03
2 Pr3+ + 2 H2O ⇌ Pr2(OH)24+ + 2 H+ –16.31 ± 0.20
3 Pr3+ + 5 H2O ⇌ Pr3(OH)54+ + 5 H+ –35.0 ± 0.3
Pr(OH)3(s) + 3 H+ ⇌ Pr3+ + 3 H2O 19.5 18.57 ± 0.20
Pr(OH)3(s) ⇌ Pr3+ + 3 OH –22.3 ± 1.0

Radium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Nordstrom et al., 1990[17]
Ra2+ + H2O ⇌ RaOH+ + H+ –13.49

Rhodium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Perrin et al., 1969[112] Baes and Mesmer, 1976[113] Brown and Ekberg[114]
Rh3+ + H2O ⇌ RhOH2+ + H+ ‒3.43 ‒3.4 ‒3.09 ± 0.1
Rh(OH)3(c) + OH ⇌ Rh(OH)4 ‒3.9

Samarium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[28] NIST46[4] Brown and Ekberg[29]
Sm3+ + H2O ⇌ SmOH2+ + H+ –7.9 –7.9 –7.84 ± 0.11
2 Sm3+ + 2 H2O ⇌ Sm2(OH)24+ + 2 H+ –14.75 ± 0.20
3 Sm3+ + 5 H2O ⇌ Sm3(OH)54+ + 5 H+ –33.9 ± 0.3
Sm(OH)3(s) + 3H+ ⇌ Sm3+ + 3H2O 16.5 17.19 ± 0.30
Sm(OH)3(s) ⇌ Sm3+ + 3 OH- –23.9 ± 0.9 (am)

–25.9 (cr)

Scandium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[115] Brown and Ekberg, 2016[116]
Sc3+ + H2O ⇌ ScOH2+ + H+ –4.3 –4.16 ± 0.05
Sc3+ + 2 H2O ⇌ Sc(OH)2+ + 2 H+ –9.7 –9.71 ± 0.30
Sc3+ + 3 H2O ⇌ Sc(OH)3 + 3 H+ –16.1 –16.08 ± 0.30
Sc3+ + 4 H2O ⇌ Sc(OH)4+ 4 H+ –26 –26.7 ± 0.3
2 Sc3+ + 2 H2O ⇌ Sc2(OH)24+ + 2 H+ –6.0 –6.02 ± 0.10
3 Sc3+ + 5 H2O ⇌ Sc3(OH)54+ + 5 H+ –16.34 –16.33 ± 0.10
Sc(OH)3(s) + 3 H+ ⇌ Sc3+ + 3 H2O 9.17 ± 0.30
ScO1.5(s) + 3 H+ ⇌ Sc3+ + 1.5 H2O 5.53 ± 0.30
ScO(OH)(c) + 3 H+ ⇌ Sc3+ + 2 H2O 9.4
Sc(OH)3(c) + OH ⇌ Sc(OH)4 –3.5 ± 0.2

Selenium(–II)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Olin et al., 2015[117] Thoenen et al., 2014[96]
H2Se(g) ⇌ H2Se(aq) –1.10 ± 0.01 –1.10 ± 0.01
H2Se ⇌ HSe + H+ –3.85 ± 0.05 –3.85 ± 0.05
HSe ⇌ Se2– + H+ –14.91 ± 0.20

Selenium(IV)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[118] Olin et al., 2005[117] Thoenen et al., 2014[96]
SeO32– + H+ ⇌ HSeO3 8.50 8.36 ± 0.23 8.36 ± 0.23
HSeO3 + H+ ⇌ H2SeO3 2.75 2.64 ± 0.14 2.64 ± 0.14

Selenium(VI)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[119] Olin et al., 2005[117] Thoenen et al., 2014[96]
SeO42‒ + H+ ⇌ HSeO4 1.360 1.75 ± 0.10 1.75 ± 0.10

Silicon

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[120] Thoenen et al., 2014[96]
Si(OH)4 ⇌ SiO(OH)3 + H+ –9.86 –9.81 ± 0.02
Si(OH)4 ⇌ SiO2(OH)22– + 2 H+ –22.92 –23.14 ± 0.09
4 Si(OH)4 ⇌ Si4O6(OH)64– + 2 H+ + 4 H2O –13.44
4 Si(OH)4 ⇌ Si4O8(OH)44– + 4 H+ + 4 H2O –35.80 –36.3 ± 0.2
SiO2(quartz) + 2 H2O ⇌ Si(OH)4 –4.0 –3.739 ± 0.087
SiO2(am) + 2 H2O ⇌ Si(OH)4 –2.714

Silver

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[121] Brown and Ekberg, 2016[122]
Ag+ + H2O ⇌ AgOH + H+ −12.0 −11.75 ± 0.14
Ag+ + 2 H2O ⇌ Ag(OH)2 + 2 H+ −24.0 −24.34 ± 0.14
0.5 Ag2O(am) + H+ ⇌ Ag+ + 0.5 H2O 6.29 6.27 ± 0.05

Sodium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[72] Nordstrom et al., 1990[17] Brown and Ekberg, 2016[123]
Na+ + H2O ⇌ NaOH + H+ –14.18 –14.18 –14.4 ± 0.2

Strontium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[16] Nordstrom et al., 1990[17] Brown and Ekberg, 2016[124]
Sr2+ + H2O ⇌ SrOH+ + H+ –13.29 –13.29 –13.15 ± 0.05

Tantalum

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[125] Filella and May, 2019a[126]
Ta(OH)5 + H+ ⇌ Ta(OH)4+ + H2O ~1 0.7007
Ta(OH)5 + H2O ⇌ Ta(OH)6 + H+ ~ –9.6
Ta6O198– + H+ ⇌ HTa6O197– 16.35
HTa6O197– + H+ ⇌ H2Ta6O196– 14.00
1/2 Ta2O5(act) + 5/2 H2O ⇌ Ta(OH)5 ~ –5.2
Ta(OH)5(s) ⇌ Ta(OH)5 –5.295
Ta2O5(s) + 5 H2O ⇌ 2 Ta(OH)5 –20.00

(a) The number of significant figures are retained to minimise propagation of round-off errors; they should not be taken to indicate the relative uncertainty of the values, which is always at least one order of magnitude less than indicated.

Tellurium(-II)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Filella and May, 2019a[127]
Te2‒ + H+ ⇌ HTe 11.81
HTe + H+ ⇌ H2Te 2.476

(a) The number of significant figures are retained to minimise propagation of round-off errors; they should not be taken to indicate the relative uncertainty of the values, which is always at least one order of magnitude less than indicated.

Tellurium(IV)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[128] Filella and May, 2019a[127]
TeO32‒ + H+ ⇌ HTeO3 9.928
HTeO3 + H+ ⇌ H2TeO3 6.445
H2TeO3 ⇌ HTeO3 + H+ ‒2.68
H2TeO3 ⇌ TeO32‒ + 2 H+ ‒12.5
H2TeO3 + H+ ⇌ Te(OH)3+ 3.13 2.415
TeO2(s) + H2O ⇌ H2TeO3 ‒4.709

(a) The number of significant figures are retained to minimise propagation of round-off errors; they should not be taken to indicate the relative uncertainty of the values, which is always at least one order of magnitude less than indicated.

Tellurium(VI)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[128] Filella and May, 2019a[127]
TeO2(OH)42‒ + H+ ⇌ TeO(OH)5 10.83
TeO(OH)5 + H+ ⇌ Te(OH)6 7.68 7.696
TeO2(OH)42‒ + 2 H+ ⇌ Te(OH)6 18.68
TeO3(OH)33‒ + 3 H+ ⇌ Te(OH)6 34.3
2 Te(OH)6 ⇌ Te2O(OH)11 + H+ ‒6.929

(a) The number of significant figures are retained to minimise propagation of round-off errors; they should not be taken to indicate the relative uncertainty of the values, which is always at least one order of magnitude less than indicated.

Terbium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[28] Brown and Ekberg, 2016[129]
Tb3+ + H2O ⇌ TbOH2+ + H+ −7.9 −7.60 ± 0.09
2 Tb3+ + 2 H2O ⇌ Tb2(OH)24+ + 2 H+ −13.9 ± 0.2
3 Tb3+ + 5 H2O ⇌ Tb3(OH)54+ + 5 H+ −31.7 ± 0.3
Tb(OH)3(s) + 3 H+ ⇌ Tb3+ + 3 H2O 16.5 16.33 ± 0.30

Thallium(I)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[130] Brown and Ekberg, 2016[131]
Tl+ + H2O ⇌ TlOH + H+ –13.21
Tl+ + OH ⇌ TlOH 0.64 ± 0.05
Tl+ + 2 OH ⇌ Tl(OH)2 –0.7 ± 0.7
½ Tl2O(s) + H+ ⇌ Tl+ + ½ H2O 13.55 ± 0.20

(a) The number of significant figures are retained to minimise propagation of round-off errors; they should not be taken to indicate the relative uncertainty of the values, which is always at least one order of magnitude less than indicated.

Thallium(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[130] Brown and Ekberg, 2016[131]
Tl3+ + H2O ⇌ TlOH2+ + H+ –0.62 –0.22 ± 0.19
Tl3+ + 2 H2O ⇌ Tl(OH)2+ + 2 H+ –1.57
Tl3+ + 3 H2O ⇌ Tl(OH)3 + 3 H+ –3.3
Tl3+ + 4 H2O ⇌ Tl(OH)4 + 4 H+ –15.0
½ Tl2O3(s) + 3 H+ ⇌ Tl3+ + ³⁄₂ H2O –3.90 –3.90 ± 0.10

(a) The number of significant figures are retained to minimise propagation of round-off errors; they should not be taken to indicate the relative uncertainty of the values, which is always at least one order of magnitude less than indicated.

Thorium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer,

1976[132]

Rand et

al., 2008[133]

Thoenen et

al, 014[134]

Brown and Ekberg,

2016[135]

Th4+ + H2O ⇌ ThOH3+ + H+ –3.20 –2.5 ± 0.5 –2.5 ± 0.5 –2.5 ± 0.5
Th4+ + 2 H2O ⇌ Th(OH)22+ + 2 H+ –6.93 –6.2 ± 0.5 –6.2 ± 0.5 –6.2 ± 0.5
Th4+ + 3 H2O ⇌ Th(OH)3+ + 3 H+ < –11.7
Th4+ + 4 H2O ⇌ Th(OH)4 + 4 H+ –15.9 –17.4 ± 0.7 –17.4 ± 0.7 –17.4 ± 0.7
2Th4+ + 2 H2O ⇌ Th2(OH)26+ + 2 H+ –6.14 –5.9 ± 0.5 –5.9 ± 0.5 –5.9 ± 0.5
2Th4+ + 3 H2O ⇌ Th2(OH)35+ + 3 H+ –6.8 ± 0.2 –6.8 ± 0.2 –6.8 ± 0.2
4Th4+ + 8 H2O ⇌ Th4(OH)88+ + 8 H+ –21.1 –20.4 ± 0.4 –20.4 ± 0.4 –20.4 ± 0.4
4Th4+ + 12 H2O ⇌ Th4(OH)124+ + 12 H+ –26.6 ± 0.2 –26.6 ± 0.2 –26.6 ± 0.2
6Th4+ + 15 H2O(l) ⇌ Th6(OH)159+ + 15 H+ –36.76 –36.8 ± 1.5 –36.8 ± 1.5 –36.8 ± 1.5
6Th4+ + 14 H2O(l) ⇌ Th6(OH)1410+ + 14 H+ –36.8 ± 1.2 –36.8 ± 1.2 –36.8 ± 1.2
ThO2(c) + 4 H+ ⇌ Th4+ + 2 H2O 6.3
ThO2(am) + 4 H+ ⇌ Th4+ + 2 H2O 8.8 ± 1.0
ThO2(am,hyd,fresh) + 4 H+ ⇌ Th4+ + 2 H2O 9.3 ± 0.9
ThO2(am,hyd,aged) + 4 H+ ⇌ Th4+ + 2 H2O 8.5 ± 0.9
Th4+ + 4 OH- ⇌ ThO2(am,hyd,fresh) + 2 H2O 46.7 ± 0.9
Th4+ + 4 OH- ⇌ ThO2(am,hyd,aged) + 2 H2O 47.5 ± 0.9

Thulium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[28] Brown and Ekberg, 2016[136]
Tm3+ + H2O ⇌ TmOH2+ + H+ −7.7 −7.34 ± 0.09
2 Tm3+ + 2 H2O ⇌ Tm2(OH)24+ + 2 H+ −13.2 ± 0.2
3 Tm3+ + 5 H2O ⇌ Tm3(OH)54+ + 5 H+ −30.5 ± 0.3
Tm(OH)3(s) + 3 H+ ⇌ Tm3+ + 3 H2O 15.0 15.56 ± 0.40

Tin(II)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Feitknecht, 1963[71] Baes and Mesmer, 1976[137] Hummel et al., 2002[45] NIST46[4] Cigala et al, 2012[138] Gamsjäger et al, 2012[139] Brown and Ekberg, 2016[140]
Sn2+ + H2O ⇌ SnOH+ + H+ –3.40 –3.8 ± 0.2 –3.4 –3.52 ± 0.05 –3.53 ± 0.40 –3.53 ± 0.40
Sn2+ + 2 H2O ⇌ Sn(OH)2 + 2 H+ –7.06 –7.7 ± 0.2 –7.1 –6.26 ± 0.06 –7.68 ± 0.40 –7.68 ± 0.40
Sn2+ + 3 H2O ⇌ Sn(OH)3 + 3 H+ –16.61 –17.5 ± 0.2 –16.6 –16.97 ± 0.17 –17.00 ± 0.60 –17.56 ± 0.40
2 Sn2+ + 2 H2O ⇌ Sn2(OH)22+ + 2 H+ –4.77 –4.8 –4.79 ± 0.05
3 Sn2+ + 4 H2O ⇌ Sn3(OH)42+ + 4 H+ –6.88 –5.6 ± 1.6 –6.88 –5.88 ± 0.05 –5.60 ± 0.47 −5.60 ± 0.47
Sn(OH)2(s) ⇌ Sn2+ + 2 OH –25.8 –26.28 ± 0.08
SnO(s) + 2 H+ ⇌ Sn2+ + H2O 1.76 2.5± 0.5 1.60 ± 0.15
SnO(s) + H2O ⇌ Sn2+ + 2 OH –26.2
SnO(s) + H2O ⇌ Sn(OH)2 –5.3
SnO(s) + 2 H2O ⇌ Sn(OH)3 + H+ –0.9

Tin(IV)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Hummel et al., 2002[45] Gamsjäger et al, 2012[139] Brown and Ekberg, 2016[140]
Sn4+ + 4 H2O ⇌ Sn(OH)4 + 4 H+ 7.53 ± 0.12
Sn4+ + 5 H2O ⇌ Sn(OH)5 + 5 H+ –1.07 ± 0.42
Sn4+ + 6 H2O ⇌ Sn(OH)62– + 6 H+ –1.07 ± 0.42
Sn(OH)4 + H2O ⇌ Sn(OH)5 + H+ –8.0 ± 0.3 –8.60 ± 0.40
Sn(OH)4 + 2 H2O ⇌ Sn(OH)62– + 2 H+ –18.4 ± 0.3 –18.67 ± 0.30
SnO2(cr) + 2 H2O ⇌ Sn(OH)4 –8.0 ± 0.2 –8.06 ± 0.11
SnO2(am) + 2 H2O ⇌ Sn(OH)4 –7.3 ± 0.3 –7.22 ± 0.08
SnO2(s) + 4 H+ ⇌ Sn4+ + 2 H2O –15.59 ± 0.04

Tungsten

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction NIST46[4]
WO42– + H+ ⇌ HWO4 3.6
WO42– + 2 H+ ⇌ H2WO4 5.8
6 WO42– + 7 H+ ⇌ HW6O215– + 3 H2O 63.83

Titanium(III)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Perrin et al., 1969[141] Baes and Mesmer, 1976[142] Brown and Ekberg, 2016[143]
Ti3+ + H2O ⇌ TiOH2+ + H+ –1.29 –2.2 –1.65 ± 0.11
2 Ti3+ + 2 H2O ⇌ Ti2(OH)24+ + 2 H+ –3.6 –2.64 ± 0.10

Titanium(IV)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[142] Brown and Ekberg, 2016[143]
Ti(OH)22+ + H2O ⇌ Ti(OH)3+ + H+ ⩽–2.3
Ti(OH)22+ + 2 H2O ⇌ Ti(OH)4 + 2 H+ –4.8
TiO2+ + H2O ⇌ TiOOH+ + H+ –2.48 ± 0.10
TiO2+ + 2 H2O ⇌ TiO(OH)2 + 2 H+ –5.49 ± 0.14
TiO2+ + 3 H2O ⇌ TiO(OH)3 + 3 H+ –17.4 ± 0.5
TiO(OH)2 + H2O ⇌ TiO(OH)3 + H+ –11.9 ±0.5
TiO2(c) +2 H2O ⇌ Ti(OH)4 ~ –4.8
TiO2(s) + H+ ⇌ TiOOH+ –6.06 ± 0.30
TiO2(s) + H2O ⇌ TiO(OH)2 –9.02 ± 0.02
TiO2 x H2O ⇌ Ti(OH)22+[OH]
TiO2(s) + 4 H+ ⇌ Ti4+ + 2 H2O –3.56 ± 0.10

Uranium(IV)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer,

1976[144]

Thoenen et

al., 2014[145]

Brown and Ekberg,

2016[146]

Grenthe et al.,

2020[6]

U4+ + H2O ⇌ UOH3+ + H+ –0.65 – 0.54 ± 0.06 –0.58 ± 0.08 – 0.54 ± 0.06
U4+ + 2 H2O ⇌ U(OH)22+ + 2 H+ (–2.6) –1.1 ± 1.0 –1.4 ± 0.2 –1.9 ± 0.2
U4+ + 3 H2O ⇌ U(OH)3+ + 3 H+ (–5.8) –4.7 ± 1.0 –5.1 ± 0.3 –5.2 ± 0.4
U4+ + 4 H2O ⇌ U(OH)4 + 4 H+ (–10.3) –10.0 ± 1.4 –10.4 ± 0.5 –10.0 ± 1.4
U4+ + 5 H2O ⇌ U(OH)5- + 5 H+ –16.0
UO2(am, hyd) + 4 H+ ⇌ U4+ + 2 H2O 1.5 ± 1.0
UO2(am,hyd) + 2 H2O ⇌ U4+ + 4 OH –54.500 ± 1.000 –54.500 ± 1.000
UO2(c) + 4 H+ ⇌ U4+ + 2 H2O –1.8
UO2(c) + 2 H2O ⇌ U4+ + 4 OH –60.860 ± 1.000

Uranium(VI)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer,

1976[147]

Grenthe et

al., 1992[148]

NIST46[4] Brown and Ekberg,

2016[149]

Grenthe et al.,

2020[6]

UO22+ + H2O ⇌ UO2(OH)+ + H+ –5.8 –5.2 ± 0.3 –5.9 ± 0.1 –5.13 ± 0.04 –5.25 ± 0.24
UO22+ + 2 H2O ⇌ UO2(OH)2 + 2 H+ ≤-10.3 –12.15 ± 0.20 –12.15 ± 0.07
UO22+ + 3 H2O ⇌ UO2(OH)3 + 3 H+ –19.2 ± 0.4 –20.25 ± 0.42 –20.25 ± 0.42
UO22+ + 4 H2O ⇌ UO2(OH)42– + 4 H+ –33 ± 2 –32.40 ± 0.68 –32.40 ± 0.68
2 UO22+ + 2 H2O ⇌ (UO2)2(OH)22+ + 2 H+ –5.62 –5.62 ± 0.04 –5.58 ± 0.04 –5.68 ± 0.05 –5.62 ± 0.08
3 UO22+ + 5 H2O ⇌ (UO2)3(OH)5+ + 5 H+ –15.63 –15.55 ± 0.12 –15.6 –15.75 ± 0.12 –15.55 ± 0.12
3 UO22+ + 4 H2O ⇌ (UO2)3(OH)42+ + 4 H+ (–11.75) –11.9 ± 0.3 –11.78 ± 0.05 –11.9 ± 0.3
3 UO22+ + 7 H2O ⇌ (UO2)3(OH)7 + 7 H+ –31 ± 2.0 –32.2 ± 0.8 –32.2 ± 0.8
4 UO22+ + 7 H2O ⇌ (UO2)4(OH)7+ + 7 H+ –21.9 ± 1.0 –22.1 ± 0.2 –21.9 ± 1.0
2 UO22+ + H2O ⇌ (UO2)2(OH)3+ + H+ –2.7 ± 1.0 –2.7 ± 1.0
UO2(OH)2(s) + 2H+ ⇌ UO22+ + 2 H2O 5.6 6.0 4.81 ± 0.20
UO3·2H2O(cr) + 2H+ ⇌ UO22+ + 3 H2O 5.350 ± 0.130

Vanadium(IV)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Brown and Ekberg, 2016[79]
VO2+ + H2O ⇌ VO(OH)+ + H+ –5.30 ± 0.13
2 VO2+ + 2 H2O ⇌ (VO)2(OH)22+ + 2 H+ –6.71 ± 0.10

Vanadium(V)

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[150] Brown and Ekberg, 2016[151]
VO2+ + 2 H2O ⇌ VO(OH)3 + H+ –3.3
VO2+ + 2 H2O ⇌ VO2(OH)2 + 2 H+ –7.3 –7.18 ± 0.12
10 VO2+ + 8 H2O ⇌ V10O26(OH)24– + 14 H+ –10.7
VO2(OH)2 ⇌ VO3(OH)2– + H+ –8.55
2 VO2(OH)2 ⇌ V2O6(OH)23– + H+ + H2O –6.53
VO3(OH)2– ⇌ VO43– + H+ –14.26
2 VO3(OH)2– ⇌ V2O74– + H2O 0.56
3 VO3(OH)2– + 3 H+⇌ V3O93– + 3 H2O 31.81
V10O26(OH)24– ⇌ V10O27(OH)5– + 3 H+ –3.6
V10O27(OH)5– ⇌ V10O286– + H+ –6.15
VO2+ + H2O ⇌ VO2OH + H+ –3.25 ± 0.1
VO2+ + 3 H2O ⇌ VO2(OH)32- + 3 H+ –15.74 ± 0.19
VO2+ + 4 H2O ⇌ VO2(OH)43- + 4 H+ –30.03 ± 0.24
2 VO2+ + 4 H2O ⇌ (VO2)2(OH)42- + 4 H+ –11.66 ± 0.53
2 VO2+ + 5 H2O ⇌ (VO2)2(OH)53- + 5 H+ –20.91 ± 0.22
2 VO2+ + 6 H2O ⇌ (VO2)2(OH)64- + 6 H+ –32.43 ± 0.30
4 VO2+ + 8 H2O ⇌ (VO2)4(OH)84- + 8 H+ –20.78 ± 0.33
4 VO2+ + 9 H2O ⇌ (VO2)4(OH)95- + 9 H+ –31.85 ± 0.26
4 VO2+ + 10 H2O ⇌ (VO2)4(OH)106- + 10 H+ –45.85 ± 0.26
5 VO2+ + 10 H2O ⇌ (VO2)5(OH)105- + 10 H+ –27.02 ± 0.34
10 VO2+ + 14 H2O ⇌ (VO2)10(OH)144- + 14 H+ –10.5 ± 0.3
10 VO2+ + 15 H2O ⇌ (VO2)10(OH)155- + 15 H+ –15.73 ± 0.33
10 VO2+ + 16 H2O ⇌ (VO2)10(OH)166- + 16 H+ –23.90 ± 0.35
½ V2O5(c) + H+ ⇌ VO2+ + ½ H2O –0.66
V2O5(s) + 2 H+ ⇌ 2 VO2+ + H2O –0.64 ± 0.09

Ytterbium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[28] Brown and Ekberg, 2016[152]
Yb3+ + H2O ⇌ YbOH2+ + H+ −7.7 −7.31 ± 0.18
Yb3+ + 2 H2O ⇌ Yb(OH)2+ + 2 H+ (−15.8)
Yb3+ + 3 H2O ⇌ Yb(OH)3 + 3 H+ (−24.1)
Yb3+ + 4 H2O ⇌ Yb(OH)4 + 4 H+ −32.7
2 Yb3+ + 2 H2O ⇌ Yb2(OH)24+ + 2 H+ −13.76 ± 0.20
3 Yb3+ + 5 H2O ⇌ Yb3(OH)54+ + 5 H+ −30.6 ± 0.3
Yb(OH)3(s) + 3 H+ ⇌ Yb3+ + 3 H2O 14.7 15.35 ± 0.20

Yttrium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[46] Brown and Ekberg, 2016[66]
Y3+ + H2O ⇌ YOH2+ + H+ –7.7 –7.77 ± 0.06
Y3+ + 2 H2O ⇌ Y(OH)2+ + 2 H+ (–16.4) [Estimation]
Y3+ + 3 H2O ⇌ Y(OH)3 + 3 H+ (–26.0) [Estimation]
Y3+ + 4 H2O ⇌ Y(OH)4-+ 4 H+ –36.5
2 Y3+ + 2 H2O ⇌ Y2(OH)24+ + 2 H+ –14.23 –14.1 ± 0.2
3 Y3+ + 5 H2O ⇌ Y3(OH)54+ + 5 H+ –31.6 –32.7 ± 0.3
Y(OH)3(s) + 3 H+ ⇌ Y3+ + 3 H2O 17.5 17.32 ± 0.30

Zinc

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[153] Powell and Brown, 2013[154] Brown and Ekberg, 2016[155]
Zn2+ + H2O ⇌ ZnOH+ + H+ −8.96 −8.96 ± 0.05 −8.94 ± 0.06
Zn2+ + 2 H2O ⇌ Zn(OH)2 + 2 H+ −16.9 –17.82 ± 0.08 −17.89 ± 0.15
Zn2+ + 3 H2O ⇌ Zn(OH)3- + 3 H+ −28.4 –28.05 ± 0.05 −27.98 ± 0.10
Zn2+ + 4 H2O ⇌ Zn(OH)42- + 4 H+ −41.2 –40.41 ± 0.12 −40.35 ± 0.22
2 Zn2+ + H2O ⇌ Zn2OH3+ + H+ −9.0 –7.9 ± 0.2 −7.89 ± 0.31
2 Zn2+ + 6 H2O ⇌ Zn2(OH)62- + 6 H+ −57.8
ZnO(s) + 2 H+ ⇌ Zn2+ + H2O 11.14 11.12 ± 0.05 11.11 ± 0.10
ε-Zn(OH)2(s) + 2 H+ ⇌ Zn2+ + 2 H2O 11.38 ± 0.20 11.38± 0.20
β1-Zn(OH)2(s) + 2 H+ ⇌ Zn2+ + 2 H2O 11.72 ± 0.04
β2-Zn(OH)2(s) + 2 H+ ⇌ Zn2+ + 2 H2O 11.76 ± 0.04
γ-Zn(OH)2(s) + 2 H+ ⇌ Zn2+ + 2 H2O 11.70 ± 0.04
δ-Zn(OH)2(s) + 2 H+ ⇌ Zn2+ + 2 H2O 11.81 ± 0.04

Zirconium

Hydrolysis constants (log values) in critical compilations at infinite dilution and T = 298.15 K:

Reaction Baes and Mesmer, 1976[55] Thoenen et al., 2014[96] Brown and Ekberg, 2016[156]
Zr4+ + H2O ⇌ ZrOH3+ + H+ 0.32 0.32 ± 0.22 0.12 ± 0.12
Zr4+ + 2 H2O ⇌ Zr(OH)22+ + 2 H+ (−1.7)* 0.98 ± 1.06* −0.18 ± 0.17*
Zr4+ + 3 H2O ⇌ Zr(OH)3+ + 3 H+ (−5.1)
Zr4+ + 4 H2O ⇌ Zr(OH)4 + 4 H+ –9.7* –2.19 ± 0.70* −4.53 ± 0.37*
Zr4+ + 5 H2O ⇌ Zr(OH)5 + 5 H+ –16.0
Zr4+ + 6 H2O ⇌ Zr(OH)62– + 6 H+ –29± 0.70 –30.5 ± 0.3
3 Zr4+ + 4 H2O ⇌ Zr3(OH)48+ + 4 H+ –0.6 0.4 ± 0.3 0.90 ± 0.18
3 Zr4+ + 5 H2O ⇌ Zr3(OH)57+ + 5 H+ 3.70
3 Zr4+ + 9 H2O ⇌ Zr3(OH)93+ + 9 H+ 12.19 ± 0.20 12.19 ± 0.20
4 Zr4+ + 8 H2O ⇌ Zr4(OH)88+ + 8 H+ 6.0 6.52 ± 0.05 6.52 ± 0.05
4 Zr4+ + 15 H2O ⇌ Zr4(OH)15+ + 15 H+ 12.58± 0.24
4 Zr4+ + 16 H2O ⇌ Zr4(OH)16 + 16 H+ 8.39± 0.80
ZrO2(s) + 4 H+ ⇌ Zr4+ + 2 H2O –1.9* –5.37 ± 0.42*
ZrO2(s, baddeleyite) + 4 H+ ⇌ Zr4+ + 2 H2O –7 ± 1.6
ZrO2(am) + 4 H+ ⇌ Zr4+ + 2 H2O –3.24± 0.10 –2.97 ± 0.18

*Errors in compilations concerning equilibrium and/or data elaboration. Data not recommended. It is strongly suggested to refer to the original papers.

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