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Acid and Base Strengths

rename
Updated 2010-04-22 15:24

Acid pKa Values

 

Stronger acids have smaller pKa values and weaker conjugate bases.

 

http://en.wikipedia.org/wiki/PKa#Values_for_common_substances
gives some values below at 25 °C in water.

 

http://en.wikipedia.org/wiki/PKa#Thermodynamics
gives some values below at 25 °C and zero ionic strength, in water.

 

Acid || pKa
Hydrogen Sulfate | 1.99
HF | 3.17
Formic Acid | 3.751
Lactic Acid | 3.86
Hydrogen Selenide | 3.89
Benzoic Acid | 4.204
Acetic Acid | 4.756
Butanoic Acid | 4.82
Propionic Acid | 4.87
HCN | 9.21
Boric Acid | 9.237
Ammonium Ion | 9.245
Phenol | 9.99
Cresol | 10.29
H2O2 | 11.7

Acid pKa Values

 

Stronger acids have smaller pKa values and weaker conjugate bases.

 

http://chemweb.unp.ac.za/chemistry/Physical_Data/pKa_values.htm
gives values below at 25 °C and links to a chart with even more values.

 

Acid || pKa
HI | -10
HBr | -9
HCl | -8
Benzenesulfonic Acid | -6.5
Sulfuric Acid | -3
Methanesulfonic Acid | -2
Hydronium Ion | -1.74
Nitric Acid | -1.5
Trifluoroacetic Acid | 0.5
Bisulfate Ion | 2
Benzoic Acid | 4.2
Anilinium Ion | 4.6
Acetic Acid | 4.8
Pyridinium Ion | 5.2
Carbonic Acid | 6.4
Thiophenol | 6.6
Hydrogen Sulfide | 7
Peracetic Acid | 8.2
Phthalimide | 8.3
Nitroethane | 8.5
Pentane-2,4-dione | 9
Ammonium Ion | 9.3
HCN | 9.3
Hexafluoroisopropanol | 9.3
Phenol | 9.9
Bicarbonate Ion | 10.3
Methanethiol | 10.3
Ethylammonium Ion | 10.8
Diethyl Malonate | 12.9
Guanidinium Ion | 13.6
Cyclopentadiene | 15
Water | 15.74
Ethanol | 16
Cyclohexanone | 16.7
Acetamide | 17
Isopropanol | 17.1
t-Butanol | 18
Acetone | 19.3
Ethyl Acetate | 25
Ethyne | 25
Acetonitrile | 25
Dimethylsulfone | 28
Dimethylsulfoxide | 35
Ammonia | 36
Diisopropylamine | 40
Toluene | 41
Benzene | 43
Propene | 43
Ethene | 44
Methane | ~60