Download Classifying Acids and Bases

Classifying Acids and
Bases
Acid and Base Theories
 There
are different ways of defining what
an acid and base is
1. Arrhenius
2. Bronstead Lowry
1. Arrhenus acids and bases
in solution

Arrhenius Acid: Chemical compound that
increases concentration of hydrogen ions H+
 Compounds
containing hydrogen
 H2 SO4

Arrhenius Base: Chemical compound that
increases concentration of hydroxide ions (OH-)
 Compounds
 NaOH
contain hydroxides

Issue: Arrhenius acids/bases must be in solution,
but scientists found that some substances acted
as acids or bases when they were NOT in a water
solution so the definition had to revised…
 Not
all acids have H, not all bases have OH
2. Bronstead-Lowry Acids and bases

Bronstead Lowry Acids: A molecule or ion that is a proton
donor

Bronstead Lowry Bases: A molecule or ion that is a proton
acceptor
**Hydrogen is a proton!!
Bronstead Lowry Reactions
 Acid
acid
+ Base→ conjugate base + conjugate
Conjugate
Base: The remainder of an acid
after H+ is released
Conjugate
Acid: The base formed by
accepting a proton
Label the following molecules as acid,
base, conjugate acid, conjugate base

Look at where the hydrogens are going!!
HCl
+
H 2O →
Cl -
HNO3 +
OH- →
H2 O
H 3 O+
+
+
NO3-
Type
Acid
Base
Arrhenius
H+ donor
OH- donor
Bronsted-Lowry Proton (H+)
donor
Proton (H+)
acceptor
Strong acids

STRONG acids and bases are considered to
completely ionize in aqueous solution.
 Good

conductors of electricity
Strong acids (memorize)
HCl, HBr, HI, HNO3, H2SO4, HClO3
Strong bases
 Strong
bases: Group 1 and 2 metal
Hydroxides (not Be or Mg)
 EX:
NaOH, Ba(OH)2 Ca(OH)2 LiOH, KOH…and NH3
All other acids/bases are considered
WEAK
WEAK acids and bases only partially ionize in water
(aqueous solution)
1.
Monoprotic acids- acids donating 1 hydrogen
Ex: HCl, HF, HNO3
2.
Diprotic acids- acids donating 2 hydrogens
Ex: H2 SO4 , H2CO3
3.
Triprotic acids- acids donating 3 hydrogens
Ex: H3PO4