pKa Table: Effect of electronegativity and resonance
Acid
pKa
HCl
-7
Cl-
H2SO4
-4
HSO4-
HNO3
-2
NO3-
H
CH3CH2O H
-2
Acidity
H
H O H
-2
O
Conjugate Base
CH3CH2OH
H2O
O
OH
H
H N H
H
5
9 (10)
O
H3N
OH
O
O Na+
10
phenol
O
phenoxide
O
OEt
acetoacetic ester
HO-H
11
15.7 (15)
OEt
HO-
16 (15) CH3CH2O-
ethanol
ethanoxide
O
H
O-
hydroxide
CH3CH2OH
H
O
H
H
O Na+
e.g.
OEt
[only most stable resonance shown here]
water
H
H
O-
e.g., sodium phenoxide
20
O-
HO- Na+
e.g., sodium hydroxide
CH3CH2O- Na+
e.g., sodium ethoxide
O- Li+
e.g., lithium enolate
enolate
[only most stable resonance shown here]
acetone
H C C Na+
e.g., sodium acetylide
H C C H
alkyne
25
H C C
acetylide
H2N-H
ammonia
35
H2Namide
H2N- Na+
e.g., sodium amide
H-H
Hygrogen
35
HHydride
H- Na+
e.g., sodium hydride
44
alkene
CH3CH2CH2CH2-H
Butane
60
CH3CH2CH2CH2Butyl carbanion
CH3CH2CH2CH2- Li+
e.g., butyl lithium
Basicity
H
H
C C
H
H