Acids and Bases
General Formula
ACID + BASE  H2O + SALT
A salt is an
ionic
compound
Comparing Acids to Bases
Naming and Writing Formulas
Acids
A compound that contains
one or more hydrogen
atoms and produces
hydrogen ions (H+) when
dissolved in water
Acids consist of an anion and
as many H+ as are
necessary to make the
atom electrically neutral.
HnX
Arrhenius Acids and Bases
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In water, an Arrhenius acid produces H3O+,
and an Arrhenius base produces OHArrhenius’ theory showed why acids and bases:
1.
have similar properties
2.
neutralize each other
3.
produce water and salt when they combine
Arrhenius’ theory could not show:
1.
2.
Why compounds without OH- could act as bases
Why reactions were not limited to occurring in
water
Bronsted-Lowry Acids and Bases
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According to Bronsted-Lowry theory, acids are
proton (H+) donors and bases are proton
acceptors (opposite of an acid)
Protons form hydronium ions, H3O+, in water
when they bond to polar water molecules
This theory:
1.
2.
expands the number of substance that can be acids
and bases
Explains how substances without OH- can be bases
Naming Acids
When an acid dissolves in water and
a hydrogen ion and a simple non metal are formed
HCl + H2O  H3O+ + Clhydrogen + water  hydronium + chloride
chloride
1.
2.
ion
ion
Use the prefix hydro in front of the nonmetal
Change the nonmetal’s ending from ide to ic acid
HCl(aq) is called hydrochloric acid
When an acid contains a polyatomic ion, the name of the
acid comes from the name of the polyatomic ion.
* the prefix hydro is not used to indicate a polyatomic ion is present
Polyatomic ions with an ate ending……..change to ic acid
HNO3(aq) + H2O(l)  H3O+ + NO3Nitric acid + water  hydronium + nitrate
ion
ion
Polyatomic ions with an ite ending……..change to ous acid
HNO2(aq) + H2O(l)  H3O+ + NO2Nitrous acid
+ water  hydronium + nitrite
ion
ion
Naming and Writing Formulas
Naming Acids
1) When the anion’s name ends in -ide, the acid’s
name begins with hydro- and the stem of the
anion’s name ends in -ic, followed by the word
acid.
Example:
Hydrochloric Acid
HCl
Anion:
Cl-
Chloride
Naming and Writing Formulas
Naming Acids
2) When the anion’s name ends in -ite, the acid’s
name is the stem of the anion with the suffix ous, followed by the word acid.
Example: Sulfurous Acid
H2SO3
Anion: Sulfite
SO32-
Naming and Writing Formulas
Naming Acids
3) When the anion’s name ends in -ate, the acid’s
name is the stem of the anion with the suffix -ic,
followed by the word acid.
Example: Nitric Acid
Anion: Nitrate
HNO3
NO3-
Naming and Writing Formulas
Writing Formulas for Acids
Use the rules for naming acids in reverse to write formulas for acids.
Find the anion in the acid. Then, match its charge with the
appropriate number of H+ ions to make the formula electrically
neutral.
Naming Bases
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Name the metal (cation) by its elemental
name
Name the simple nonmetal (anion) with
the ide ending
Name the polyatomic ion as is (example
OH- is hydroxide)
Names and Formulas for Bases
An ionic compound that produces hydroxide ions (OH-) when
dissolved in water.
These are named in the same way as other ionic compounds: cation
first and anion second.
Common Bases
NaOH
Sodium Hydroxide
Ba(OH)2
Barium Hydroxide
Ca(OH)2
Calcium Hydroxide
pH Scale

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The amount
of H3O+ ions
in solution
determines
whether a
solution is an
acid or base.
pH measures
the
concentration
of H+ ions in
a solution
pH Scale
ACIDS weak
weak
BASES strong
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Strong
neutral
10-1
10-7
10-14
Concentration of H3O+ ions (moles/litre)
Acids increase
p+ concentration
Bases decrease
p+ concentration
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In aqueous solution, a strong acid donates
nearly all of its protons to water, whereas
a weak acid donates only a small
percentage of protons to water.
Most hydroxides of Groups 1A and 2A are
strong gases, which dissociate nearly
completely in water
Adding water equalizes the strength of all
strong acids/bases = levelling effect
Conjugate Pairs
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Acids and bases react differently but are connected in
similar reactions
Once an acid donates a proton it is then able to accept
another proton
= conjugate acid-base pair (strengths are inverse)
Practice
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