electronegativities
F
Cl
Br
I
C
N
O
perchloric acid
HClO4
strong acid
Ka > 107
chloric acid
HClO3
strong acid
Ka ≈ 1
chlorous acid
HClO2
Ka = 1.2 x 10-2
acetic acid (ethanoic acid)
benzoic acid
Ka = 1.85 x 10-5
Ka = 6.25 x 10-5
hypochlorous acid
HClO or HOCl
Ka = 3.5 x 10-8
4-fluorobenzoic acid
hypobromous acid
HBrO or HOBr
Ka = 2.0 x 10-9
4-chlorobenzoic acid
hypoiodous acid
HIO or HOI
Ka = 2.0 x 10-11
4-bromobenzoic acid
hydrofluoric acid
HF
Ka = 7.2 x 10-4
4-iodobenzoic acid
HF bond is unusually
strong due to proximity
of the very small
fluoride ion
3.98
3.16
2.96
2.66
2.55
3.04
3.44
● strong acids dissociate (ionize) completely in water
● no equilibrium; rxn goes to completion
HCl(aq) → H+(aq) + Cl-(aq)
● weak acids are only partially dissociated; equilibrium exists
HF(aq) ↔ H+(aq) + F-(aq)
● 0.1 M HF has >90% of HF molecules undissociated
● 3 ways to measure if acid is WEAK or STRONG:
(1) electrical conductivity
(2) colligative properties
(3) pH determination
● 6 famous strong acids: HCl, HBr, HI, HNO3, H2SO4, HClO4
fluoroacetic acid (fluoroethanoic acid)
Ka = 2.57 x 10-3
Ka = 7.08 x 10-5
chloroacetic acid (chloroethanoic acid)
Ka = 1.35 x 10-3
Ka = 1.00 x 10-4
bromoacetic acid (bromoethanoic acid)
Ka = 1.26 x 10-3
Ka = 1.10 x 10-4
iodoacetic acid (iodoethanoic acid)
Ka = 6.60 x 10-4
Ka = 1.00 x 10-4
H2O
Ka = 1.00 x 10-14
H2S
Ka = 1.12 x 10-8
H2Se
Ka = 7.76 x 10-4
H2Te
Ka = 3.98 x 10-3