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 |
