Ionization Constants of Inorganic Acids

perchloric acid

HClO₄

ca. 10¹⁰

ca. -10

hydrogen iodide

HI

ca. 10⁹

ca. -9

hydrogen bromide

HBr

ca. 10⁹

ca. -9

hydrogen chloride

HCl

ca. 10⁷

ca. -7

nitric acid

HNO₃

ca. 200

ca. -2

thiocyanic acid

HSCN

70

-1.85

hydronium ion

H₃O⁺

55

-1.74

chloric acid

HClO₃

10

-1.0

iodic acid

HIO₃

0.18

0.75

hypophosphorous acid

H₂P(O)OH

10^-2

2.0

hydrogen fluoride

HF

6.6 * 10^-4

3.2

nitrous acid

HNO₂

5.0 * 10^-4

3.3

cyanic acid

HOCN

3.54 * 10^-4

3.45

hydrazoic acid

HN₃

2.37 * 10^-5

4.63

hypochlorous acid

HOCl

2.95 * 10^-8

7.53

hypobromous acid

HOBr

2.3 * 10^-9

8.65

hydrocyanic acid

HCN

5.8 * 10^-10

9.25

ammonium

NH₄⁺

5.8 * 10^-10

9.25

hypoiodous acid

HOI

10^-10

10

hydrogen peroxide

H₂O₂

2.5 * 10^-12

11.6

water

H₂O

1.82 * 10^-16

15.74

heavy water

D₂O

3.5 * 10^-17

16.55

ammonia

NH₃

ca. 10^-34

ca. 34

Organic Chemistry
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sulfuric acid

H₂SO₄
HSO₄^-1

K₁ = 2.4 * 10⁶
K₂ = 1.0 * 10^-2

-6.62
1.99

chromic acid

H₂CrO₄
HCrO₄^-1

K₁ = 3.55
K₂ = 3.36 * 10^-7

-0.55
6.47

sulfurous acid

H₂SO₃
HSO₃^-1

K₁ = 1.71 * 10^-2
K₂ = 5.98 * 10^-8

1.77
7.22

phosphoric acid

H₃PO₄
H₂PO₄^-1
HPO₄^-2

K₁ = 7.1 * 10^-3
K₂ = 6.2 * 10^-8
K₃ = 4.6 * 10^-13

2.15
7.21
12.34

phosphorous acid

H₃PO₃
H₂PO₃^-1

K₁ = 1.6 * 10^-2
K₂ = 6.3 * 10^-7

1.8
6.2

pyrophosphoric acid

H₄P₂O₇
H₃P₂O₇^-1
H₂P₂O₇^-2
HP₂O₇^-3

K₁ = 3 * 10^-2
K₂ = 4.4 * 10^-3
K₃ = 2.5 * 10^-7
K₄ = 5.6 * 10^-10

1.52
2.36
6.60
9.25

carbonic acid

H₂CO₃
HCO₃^-1

K₁ = 4.35 * 10^-7
K₂ = 4.69 * 10^-11

6.36
10.33

hydrogen sulfide

H₂S
HS^-1

K₁ = 9 * 10^-8
K₂ = ca.10^-15

6.97
ca.15

boric acid

H₃BO₃
H₂BO₃^-1
HBO₃^-2

K₁ = 7.2 * 10^-10
K₂ = 1.8 * 10^-13
K₃ = 1.6 * 10^-14

9.14
12.7
13.8

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