Conjugate Acid-Base Pairs Arranged by Strength
The stronger the acid, the weaker its conjugate base. The stronger the base, the weaker its conjugate acid.
Conjugate bases of diprotic acids are often atypical (see entries in italics for examples).
ACID |
BASE |
||||
Strength
of Acid |
Name |
Formula |
Formula |
Name |
Strength
of Base |
STRONGACIDS |
perchloric acid |
HClO4 |
ClO4– |
perchlorate ion |
Neutral Anion |
sulfuric acid |
H2SO4 |
HSO4– |
hydrogensulfate ion |
Moderately Strong Acid! |
|
hydroiodic acid |
HI |
I– |
iodide ion |
Neutral Anions |
|
hydrobromic acid |
HBr |
Br– |
bromide ion |
||
hydrochloric acid |
HCl |
Cl– |
chloride ion |
||
nitric acid |
HNO3 |
NO3– |
nitrate ion |
||
Strong
Acid |
hydronium ion |
H3O+ |
H2O |
water |
Neutral |
Moderately Strong Acid |
hydrogensulfate ion |
HSO4– |
SO42– |
sulfate ion |
Neutral Anion! |
WEAK ACIDS Acid strength INCREASES as you go UP the column. |
hydrofluoric acid |
HF |
F– |
fluoride ion |
WEAK BASES Base strength INCREASES as you go DOWN the column. |
nitrous acid |
HNO2 |
NO2– |
nitrite ion |
||
acetic acid |
HC2H3O2 |
C2H3O2– |
acetate ion |
||
carbonic acid |
H2CO3 |
HCO3– |
hydrogencarbonate ion |
||
hydrosulfuric acid |
H2S |
HS– |
hydrogensulfide ion |
||
ammonium ion |
NH4+ |
NH3 |
ammonia |
||
hydrocyanic acid |
HCN |
CN– |
cyanide ion |
||
Basic
Anion! |
hydrogencarbonate ion |
HCO3– |
CO32– |
carbonate ion |
|
Weak Acid |
methylammonium ion |
CH3NH3+ |
CH3NH2 |
methylamine |
|
Neutral |
water |
H2O |
OH– |
hydroxide ion |
Strong
Base |
Neutral Molecules |
ammonia |
NH3 |
NH2– |
amide ion |
STRONG BASES |
hydrogen |
H2 |
H– |
hydride ion |
||
methane |
CH4 |
CH3– |
methide ion |
||
Strong Base! |
hydroxide ion |
OH– |
O2– |
oxide ion |