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Appendix H: Ionization Constants of Weak Acids
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Ionization Constants of Weak Acids
|
Acid
|
Formula
|
K
a
at 25 °C
|
Lewis Structure
|
|
acetic
|
CH
3
CO
2
H
|
1.8 × 10
−5
|
|
|
arsenic
|
H
3
AsO
4
|
5.5 × 10
−3
|
|
|
|
1.7 × 10
−7
|
|
|
5.1 × 10
−12
|
|
arsenous
|
H
3
AsO
3
|
5.1 × 10
−10
|
|
|
boric
|
H
3
BO
3
|
5.4 × 10
−10
|
|
|
carbonic
|
H
2
CO
3
|
4.3 × 10
−7
|
|
|
|
4.7 × 10
−11
|
|
cyanic
|
H
CNO
|
2 × 10
−4
|
|
|
formic
|
HCO
2
H
|
1.8 × 10
−4
|
|
|
hydrazoic
|
H
N
3
|
2.5 × 10
−5
|
|
|
hydrocyanic
|
H
CN
|
4.9 × 10
−10
|
|
|
hydrofluoric
|
H
F
|
3.5 × 10
−4
|
|
|
hydrogen peroxide
|
H
2
O
2
|
2.4 × 10
−12
|
|
|
hydrogen selenide
|
H
2
Se
|
1.29 × 10
−4
|
|
|
H
Se
–
|
1 × 10
−12
|
|
|
hydrogen sulfate ion
|
|
1.2 × 10
−2
|
|
|
hydrogen sulfide
|
H
2
S
|
8.9 × 10
−8
|
|
|
H
S
–
|
1.0 × 10
−19
|
|
|
hydrogen telluride
|
H
2
Te
|
2.3 × 10
−3
|
|
|
H
Te
–
|
1.6 × 10
−11
|
|
|
hypobromous
|
H
BrO
|
2.8 × 10
−9
|
|
|
hypochlorous
|
H
ClO
|
2.9 × 10
−8
|
|
|
nitrous
|
H
NO
2
|
4.6 × 10
−4
|
|
|
oxalic
|
H
2
C
2
O
4
|
6.0 × 10
−2
|
|
|
|
6.1 × 10
−5
|
|
phosphoric
|
H
3
PO
4
|
7.5 × 10
−3
|
|
|
|
6.2 × 10
−8
|
|
|
4.2 × 10
−13
|
|
phosphorous
|
H
3
PO
3
|
5 × 10
−2
|
|
|
|
2.0 × 10
−7
|
|
sulfurous
|
H
2
SO
3
|
1.6 × 10
−2
|
|
|
|
6.4 × 10
−8
|