Appendix
Ionization Constants for Select Acids
Ka determined at 25 °C.
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| Acid | Formula and Ionization Equation | Ka | pKa |
|---|---|---|---|
|
Acetic
|
CH3COOH + H2O ⇌ H3O+ + CH3COO−
|
1.8 × 10−5
|
4.74 |
|
Arsenic
|
H3AsO4 + H2O ⇌ H3O+ + H2AsO4−
|
K1 = 6.17 × 10−3
|
2.210 |
|
H2AsO4− + H2O ⇌ H3O+ + HAsO42−
|
K2 = 1.17 × 10−7
|
6.932 | |
|
HAsO42− + H2O ⇌ H3O+ + AsO43−
|
K3 = 3.09 × 10−12
|
11.523 | |
|
Benzoic
|
C6H5COOH + H2O ⇌ H3O+ + C6H5COO−
|
1.2 × 10−4
|
3.92 |
|
Boric
|
B(OH)3(H2O) + H2O ⇌ H3O+ + B(OH)4−
|
5.8 × 10−10
|
9.24 |
|
Carbonic
|
H2CO3 + H2O ⇌ H3O+ + HCO3−
|
K1 = 4.3 × 10−7
|
6.37 |
|
HCO3− + H2O ⇌ H3O+ + CO32−
|
K2 = 4.7 × 10−11
|
10.33 | |
|
Citric
|
H3C6H5O7 + H2O ⇌ H3O+ + H2C6H5O7−
|
K1 = 1.4 × 10−3
|
2.85 |
|
H2C6H5O7− + H2O ⇌ H3O+ + HC6H5O72−
|
K2 = 4.5 × 10−5
|
4.35 | |
|
HC6H5O72− + H2O ⇌ H3O+ + C6H5O73−
|
K3 = 1.5 × 10−6
|
5.82 | |
|
Chlorous
|
HClO2 + H2O ⇌ H3O+ + ClO2−
|
1.1 × 10−2
|
1.96 |
|
Formic
|
HCOOH + H2O ⇌ H3O+ + HCOO−
|
3.0 × 10−4
|
3.52 |
|
Hydrazoic
|
HN3 + H2O ⇌ H3O+ + N3−
|
1.0 × 10−5
|
5.00 |
|
Hydrocyanic
|
HCN + H2O ⇌ H3O+ + CN−
|
3.3 × 10−10
|
9.48 |
|
Hydrofluoric
|
HF + H2O ⇌ H3O+ + F−
|
6.8 × 10−4
|
3.17 |
|
Hydrogen peroxide
|
H2O2 + H2O ⇌ H3O+ + HO2−
|
2.1 × 10−12
|
11.68 |
|
Hydrosulfuric†
|
H2S + H2O ⇌ H3O+ + HS−
|
K1 = 1 × 10−7
|
7.0 |
|
HS− + H2O ⇌ H3O+ + S2−
|
K2 = 1 × 10−19
|
19.0 | |
|
Hypochlorous
|
HOCl + H2O ⇌ H3O+ + OCl−
|
6.8 × 10−8
|
7.17 |
|
Nitrous
|
HNO2 + H2O ⇌ H3O+ + NO2−
|
7.41 × 10−4
|
3.130 |
|
Oxalic
|
H2C2O4 + H2O ⇌ H3O+ + HC2O4−
|
K1 = 5.5 × 10−2
|
1.26 |
|
HC2O4− + H2O ⇌ H3O+ + C2O42−
|
K2 = 1.4 × 10−4
|
3.85 | |
|
Phenol
|
HC6H5O + H2O ⇌ H3O+ + C6H5O−
|
1.7 × 10−10
|
9.77 |
|
Phosphoric
|
H3PO4 + H2O ⇌ H3O+ + H2PO4−
|
K1 = 7.2 × 10−3
|
2.14 |
|
H2PO4− + H2O ⇌ H3O+ + HPO42−
|
K2 = 6.3 × 10−8
|
7.20 | |
|
HPO42− + H2O ⇌ H3O+ + PO43−
|
K3 = 4.6 × 10−13
|
12.34 | |
|
Phosphorous
|
H3PO3 + H2O ⇌ H3O+ + H2PO3−
|
K1 = 2.4 × 10−2
|
1.62 |
|
H2PO3− + H2O ⇌ H3O+ + HPO32−
|
K2 = 2.9 × 10−7
|
6.54 | |
|
Propanoic
|
CH3CH2COOH + H2O ⇌ H3O+ + CH3CH2COO−
|
1.33 × 10−5
|
4.85 |
|
Selenic
|
H2SeO4 + H2O ⇌ H3O+ + HSeO4−
|
K1 = very large
|
--- |
|
HSeO4− + H2O ⇌ H3O+ + SeO42−
|
K2 = 2.2 × 10−2
|
1.66 | |
|
Selenous
|
H2SeO3 + H2O ⇌ H3O+ + HSeO3−
|
K1 = 2.5 × 10−3
|
2.60 |
|
HSeO3− + H2O ⇌ H3O+ + SeO32−
|
K2 = 1.6 × 10−9
|
8.80 | |
|
Sulfuric
|
H2SO4 + H2O ⇌ H3O+ + HSO4−
|
K1 = very large
|
--- |
|
HSO4− + H2O ⇌ H3O+ + SO42−
|
K2 = 1.1 × 10−2
|
1.96 | |
|
Sulfurous
|
H2SO3 + H2O ⇌ H3O+ + HSO3−
|
K1 = 1.7 × 10−2
|
1.77 |
|
HSO3− + H2O ⇌ H3O+ + SO32−
|
K2 = 6.3 × 10−8
|
7.2 | |
|
Tellurous
|
H2TeO3 + H2O ⇌ H3O+ + HTeO3−
|
K1 = 7.1 × 10−7
|
6.15 |
|
HTeO3− + H2O ⇌ H3O+ + TeO32−
|
K2 = 4.0 × 10−9
|
8.40 | |
| Taken from Hogfeldt, E. and Perrin, D. D., Stability Constants of Metal-Ion complexes, 1st ed. Oxford: New York: Pergamon, 1979-1982. International Union of Pure and Applied Chemistry Commission on Equilibrium Data. †From Myers, R., Journal of Chemical Education, Vol. 63, 1986, pp. 687-690. |
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Ionization Constants for Select Bases
Kb determined at 25 °C.
| Base | Formula and Ionization Equation | Kb | pKb |
|---|---|---|---|
|
Ammonia‡
|
NH3 + H2O ⇌ NH4+ + OH−
|
1.77 × 10−5
|
4.752 |
|
Aniline§
|
C6H5NH2 + H2O ⇌ C6H5NH3+ + OH−
|
3.9 × 10−10
|
9.41 |
|
Dimethylamine§
|
(CH3)2NH + H2O ⇌ (CH3)2NH2+ + OH−
|
5.8 × 10−4
|
3.24 |
|
Ethylenediamine
|
(CH2)2(NH2)2 + H2O ⇌ (CH2)2(NH2)2H+ + OH−
|
K1 = 7.8 × 10−5
|
4.11 |
|
(CH2)2(NH2)2H+ + H2O ⇌ (CH2)2(NH2)2H22+ + OH−
|
K2 = 2.1 × 10−8
|
7.68 | |
|
Hydrazine
|
N2H4 + H2O ⇌ N2H5+ + OH−
|
K1 = 1.2 × 10−6
|
5.92 |
|
N2H5+ + H2O ⇌ N2H62+ + OH−
|
K2 = 1.3 × 10−15
|
14.89 | |
|
Hydroxylamine
|
NH2OH + H2O ⇌ NH3OH+ + OH−
|
9.3 × 10−9
|
8.03 |
|
Methylamine
|
CH3NH2 + H2O ⇌ CH3NH3+ + OH−
|
5.0 × 10−4
|
3.30 |
|
Pyridine
|
C5H5N + H2O ⇌ C5H5NH+ + OH−
|
1.6 × 10−9
|
8.80 |
|
Trimethylamine§
|
(CH3)3N + H2O ⇌ (CH3)3NH+ + OH−
|
6.2 × 10−5
|
4.21 |
| Taken from Hogfeldt, E. and Perrin, D. D., Stability Constants of Metal-Ion complexes, 1st ed. Oxford: New York: Pergamon, 1979-1982. International Union of Pure and Applied Chemistry Commission on Equilibrium Data. ‡From Read, A. J., Journal of Solution Chemistry, Vol. 11, No. 9, 1982, pp. 649-664. §From Meites, L., Ed. Handbook of Analytical Chemistry, 1st ed. New York: McGraw-Hill, 1963. |
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