Dissociation constants of acids and bases

Acid & Base Dissociation Constants

 

Dissociation constants of acids and bases k_a and k_b respectively at 25 °C are shown in Table 1 and Table 2 :

 

Table 1: Dissociation Constants for Acids at 25 °C

Name	Formula	ka1	ka2	ka3
Acetic acid	CH3COOH	1.8 * 10-3
Arsenic acid	H3AsO4	5.6 * 10-5	1.0 * 10-7	3.0 * 10-12
Arsenous acid	H3AsO3	5.1 * 10-10
Ascorbic acid	H2C6H6O6	8.0 * 10-5	1.6 * 10-12
Benzoic acid	C6H5COOH	6.3 * 10-5
Boric acid	H3BO3	5.8 * 10-10
Butanoic acid	C3H7COOH	1.5 * 10-5
Carbonic acid	H2CO3	4.3 * 10-7	5.6 * 10-11
Chloroacetic acid	CH2ClCOOH	1.4 * 10-3
Chlorous acid	HClO2	1. 1 * 10-2
Citric acid	HOOCC(OH)	7.4 * 10-4	1.7 * 10-5	4.0 * 10-7
Cyanic acid	HCNO	3.5 * 10-4
Formic acid	HCOOH	1.8 * 10-4
Hydroazoic acid	HN3	1.9 * 10-5
Hydrocyanic acid	HCN	4.9 * 10-10
Hydrofluoric acid	HF	6.8 * 10-4
Hydrogen chromate	HCrO4-	3.0 * 10-7
Hydrogen peroxide	H2O2	2.4 * 10-12
Hydrogen selenate	HSeO4-	2.2 * 10-2
Hydrogen sulfide	H2S	9.5 * 10-8	1.0 * 10-19
Hypobromous acid	HBrO	2.5 * 10-9
Hypochlorous acid	HClO	3.0 * 10-8
Hypoiodous acid	HIO	2.3 * 10-11
Iodic acid	HIO3	1.7 * 10-1
Lactic acid	HC3H5O3	1.4 * 10-4
Malonic acid	H2C3H2O4	1.5 * 10-3	2.0 * 10-6
Nitrous acid	HNO2	4.5 * 10-4
Oxalic acid	(COOH)2	5.9 * 10-2	6.4 * 10-5
Phenol	C6H5OH	1.3 * 10-10
Phosphoric acid	H3PO4	7.5 * 10-3	6.2 * 10-8	4.2 * 10-13
Propionic acid	C2H5COOH	1.3 * 10-5
Pyrophosphoric acid	H4P2O7	3.0 * 10-2	4.4 * 10-3	2.1 * 10-7
Selenous acid	H2SeO3	2.3 * 10-3	5.3 * 10-9
Sulfuric acid	H2SO4	Strong acid	1.2 * 10-2
Sulfurous acid	H2SO3	1.7 * 10-2	6.4 * 10-8
Tartaric acid	H2C4H4O6	1.0 * 10-3

 

Table 2: Dissociation Constants for Bases at 25 °C

Name	Formula	kb1	kb2	kb3
Ammonia	NH3	1.8 * 10-5
Aniline	C6H5NH2	4.3 * 10-10
Dimethylamine	(CH3)2NH	5.4 * 10-4
Ethylamine	C2H5N2	6.4 * 10-4
Hydrazine	H2NNH2	1.3 * 10-6
Hydroxylamine	HONH2	1.1 * 10-8
Methylamine	CH3NH2	4.4 * 10-4
Pyridine	C5H5N	1.7 * 10-9

 

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Relevant Posts

Solubility Product Constants

 

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References

1. CRC Handbook of Chemistry and Physics, 52nd edition, The Chemical Rubber Co., (1971)
2. David W. Oxtoby, H.P. Gillis, Alan Campion, “Principles of Modern Chemistry”, Sixth Edition, Thomson Brooks/Cole, 2008
3. Steven S. Zumdahl, “Chemical Principles”  6th Edition, Houghton Mifflin Company, 2009

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Key Terms

acid dissociation contants, base dissociation constants, aqueous equilibrium constants, acid, base,

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