Unit VII
Chapter 15
Properties
• Both acids and bases ionize or dissociate
in water
• Acids: taste sour, conduct electricity,
cause certain indicators to change color,
and react with metals to form H2 gas
• Bases: taste bitter, feel slippery, conduct
electricity, and cause certain indicators to
change color
Recognizing Acids and
Bases
• Most simply, acids tend to have H’s at
the beginning of their chemical
formulas.
• Bases tend to have OH’s at the end of
their formulas.
• NOTE: THIS IS NOT THE WHOLE
TRUTH...YOU’LL LEARN MORE SOON!
Naming Acids and
Bases
• REVIEW:
• Binary acids
• Oxyacids
• Bases (named simply as ionic compounds)
• pg. 454-458
Acid Nomenclature Review
Anion
Ending
Binary 
Acid Name
-ide
hydro-(stem)-ic acid
-ate
(stem)-ic acid
-ite
(stem)-ous acid
oxyacid
An easy way to remember which goes with which…
“In the cafeteria, you ATE something ICky”
Practice Problems
Answers:
1.
2.
3.
4.
HF
HNO3
KOH
H2SO4
1. Hydrofluoric acid
2. Nitric acid
3. Potassium
hydroxide
4. Sulfuric acid
Practice Problem
Answers:
1.
2.
3.
4.
Chromic acid
Iron (II) hydroxide
Acetic Acid
Lithium hydroxide
1. H2CrO4
2. Fe(OH)2
3. CH3COOH
4. LiOH
Acid/Base Strength
• The Strength of an acid/base depends
on the degree of
ionization/dissociation.
• Common Aqueous Acids and Bases:
Tables 15-3 and 15-4
Acid/Base Definitions
• Arrhenius Acids/Bases
• Earliest and most specific definition
• Brønted-Lowry Acids/Bases
• Middle definition
• Lewis Acids/Bases
• Latest and most general definition
Arrhenius Acid Definition
• An acid is a compound that increases
hydrogen ions [H+] concentration
when dissolved in water.
• Ex. HCl(g) is named hydrogen chloride.
BUT HCl(aq) is named hydrochloric acid.
Arrhenius Base Definition
• A base is a compound that increases
hydroxide ion [OH-] concentration
when dissolved in water.
• Ex. NaOH(s) is named sodium hydroxide
and is NOT a base.
BUT NaOH (aq) is named sodium hydroxide
and IS a base.
Acidic Solutions
• An acidic solution is one in which [H3O+] is
greater than [OH-].
• Ex.
• HCl(g)
H 2O
H+ (aq) + Cl- (aq)
• Since the water is already forming some H+ ions
(typically in the form of H3O+), the HCl is adding
more H+ ions. This causes there to be MORE H+
or H3O+ ions than OH- ions.
Basic Solutions
• A basic solution is one in which [OH-] is
greater than [H3O+].
• AKA: alkaline solutions
• Ex.
• NaOH(s)
H2O
Na+(aq) + OH-(aq)
• Since the water is already forming some OHions, NaOH is adding more OH- ions. This causes
there to be MORE OH- ions than H3O+ ions.
Arrhenius Acids and
Bases
• Acids are hydrogen-containing compounds
that ionize to yield hydrogen ions in
aqueous solution...
• Bases are compounds that ionize to yield
hydroxide ions in aqueous solution...
• BUT...NH3 is a base! Arrhenius’ theory
doesn’t hold up in every case, so...
Brønsted-Lowry Acids
and Bases
• An acid is a hydrogen-ion donor, and a base
is a hydrogen-ion acceptor.
• A substance that can either accept or
donate depending upon its partner is call
amphoteric.
• Example:
NH3(aq) + H2O(l)
NH4+(aq) + OH-(aq)
• Watch the compounds as they react. What
happens across the arrow?
Practice Problem
• H2SO4 + H2O
H3O+ + HSO4-
• Label the acid, base, conjugate acid,
and conjugate base.
Lewis Acid/Base
Definition
Lewis acid - a
substance that
accepts an
electron pair
Lewis base - a
substance that
donates an electron
pair
Lewis Acids & Bases
Formation of hydronium ion is also an
excellent example.
H
+
ACID
•• ••
O—H
H
BASE
••
H O—H
H
•Electron pair of the new O-H bond
originates on the Lewis base.
Lewis Acid/Base
Reaction
Conjugate Acids and
Bases
• Every acid on the left side of the
reaction equation has a conjugate
base on the right side of the equation.
• There is also the same base/conjugate
acid pairing in each equation.
Conjugate pairs
Practice problems
Identify the acid, base, conjugate acid,
conjugate base, and conjugate acid-base pairs:
HC2H3O2(aq) + H2O(l)  C2H3O2–(aq) + H3O+(aq)
acid
base
conjugate base conjugate acid
conjugate acid-base pairs
OH –(aq) + HCO3–(aq)  CO32–(aq) + H2O(l)
base
acid
conjugate base conjugate acid
conjugate acid-base pairs
Strength of conjugates
• The stronger the acid/base, the
weaker the conjugate base/acid is.
• See Table 15-6 p.471
• Ex: HCl(acid)-Strong acid
Cl-(conj. base)-very weak base
Neutral Solutions
• Any aqueous solution in which [OH-] =
[H3O+] is described as a neutral
solution.
• Ex. Pure water
• Neutralization Reactions are based on
equalizing the conc. of acids and bases in
solution. (Titration)