1. Lecture /27/06

2. Molecular structure and acid strength
Binary Acids
Within group:
Across Row:

3. Molecular structure and acid strength
Oxoacids with different central atoms
H-O-Z-
HOCl
HOBr
HOI Ka
3.5 x 10-8
2.5 x 10-9
2.3 x 10-11
electronegativity
Cl (3.0)
Br (2.8)
I (2.5)

4. Molecular structure and acid strength
Oxoacids with the same central atom
HOCl
HClO2
HClO3
HClO4 Ka
3.5 x 10-8
1.1 x 10-2
~ 103
~ 108
HNO2 vs. HNO3
H2SO3 vs. H2SO4

5. Carboxylic Acids (R-COOH)
Acid strength related to R
C5H11-COOH
CH3-COOH
CH2Cl-COOH
CCl3-COOH Ka
1.4 x 10-5
1.8 x 10-5
1.4 x 10-3
3 x 10-1
hexanoic acid
Acetic acid
Chloroacetic acid
trichloroacetic acid

6. Assign pH: (≤ 2, 2-6, 6-8, 8-12, ≥ 12) No calculators
0.1 M solutions
HNO2
NH4Cl
NaF
Mg(CH3COO-)2
BaO
KHSO4
NaHCO3
BaCl2

7. Put in order high pH to low (0.1 M solutions)
KNO3
Na2SO4
CaO
HBr
C6H5COOH
NaH