pKa Values for Organic and Inorganic Brönsted Acids at 25 °C


  • Acid strengths decrease down the table. Conjugate base strengths increase down the table.
  • From the Online Web Learning Web page - McMurry Web Site.
  • From E. P. Serjeant and B. Dempsey (eds.), Ionization Constants of Organic Acids in Solution, IUPAC Chemical Data Series No. 23, Pergamon Press, Oxford, UK, 1979.
  • If you need more pKa values, download this PDF file.
Name

Acid/Conjugate Base

pKa

Hydroiodic acid

-10

Hydrobromic acid

-9

Hydrochloric acid

-8

Acetone conjugate acid

-7

Benzenesulfonic acid

-6.5

Acetic acid conjugate acid

-6

Diethyl ether conjugate acid

-3.5

Sulfuric acid

-3

Ethanol conjugate acid

-2

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

Hydrogen cyanide

9.3

Hexaflurorisopropanol

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

Diemthylsulfoxide

35

Ammonia

36

Diisopropylamine

40

Toluene

41

Benzene

43

Propene

43

Ethene

44

Methane

approx. 60

Last updated: March 02, 2007

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