Acids and
bases
Properties of acids &
bases
15-1 objectives
• List 5 general properties of aqueous acids
and bases
• Name common binary acids and oxyacids
• List 5 common industrial and laboratory
acids and give 2 properties of each
• Define Arrhenius acids and bases
• Explain the difference between strong
and weak acids and bases
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Properties of Acids
1. Taste sour
2. Change the color of pH indicators
(turn blue litmus paper red)
3. React with active metals to produce
hydrogen gas
4. React with bases to produce salts
and water
5. Conduct an electric current
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Properties of Bases
1. Taste bitter
2. Change the color of acid-base indicators
(turn red litmus paper blue)
3. Feel slippery
4. React with acids to produce salts and
water
5. Conduct an electric current
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Commonly Used Acids
Sulfuric acid (H2SO4)
dehydrating agent; batteries; metals, paper; dyes, paints
& detergents
Nitric acid (HNO3)
stains proteins yellow; very smelly; explosives
Phosphoric acid (H3PO4)
fertilizer; ceramics; detergents; flavoring
Hydrochloric acid (HCl)
“pickling” metals; food processing; pools; cleaning
masonry
Acetic acid (CH3COOH)
smelly; vinegar; freezes at 17oC; plastics; fungicide
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Arrhenius Acid & Bases
Arrhenius acid – increases the
concentration of hydrogen ions in
aqueous solution
HNO3(l) + H2O(l)  H3O (aq) + NO3 (aq)
+
-
The H3O+ ion is called the hydronium ion
Arrhenius base – increases the
concentration of hydroxide ions in
aqueous solutions
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Strong Acids
Strong acids ionize completely in aqueous
solutions and are strong electrolytes
Examples:
H2SO4
HClO4
HCl
HNO3
HBr
HI
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Weak Acids
Do not ionize completely and are weak electrolytes
Examples:
H3PO4
CH3COOH
H2CO3
H2S
HCN
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Strong Bases
A strong base completely dissociates in
water to produce OH- ions
Solutions are called alkaline
Examples:
NaOH
KOH
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Weak Bases
Weak bases do not dissociate completely in
solution
Example:
NH3
C6H5NH2 (aniline)
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Acid-Base Theories
15-2 Objectives
• Define and recognize Brønsted-Lowry
acids and bases
• Define a Lewis acid and a Lewis base
• Name compounds that are acids
under the Lewis definition but are not
acids under the Brønsted-Lowry
definition
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Brønsted-Lowry Acids
• A molecule or ion that is a proton donor is
Brønsted-Lowry acid
Example:
HCl dissolved in ammonia
HCl dissolved in water
H2O dissolved in ammonia
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Brønsted-Lowry Bases
• A molecule or ion that accepts a proton is
a Brønsted-Lowry base
Example:
HCl dissolved in ammonia
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Monoprotic Acids
Monoprotic acids can donate only one proton
Example:
+
HCl(g) + H2O(l)  H3O (aq) + Cl (aq)
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Polyprotic Acids
Polyprotic acids can donate more than one
proton
Example:
+
H2SO4(l) + H2O(l)  H3O (aq) + HSO4 (aq)
+
2HSO4 (aq) + H2O(l)  H3O (aq) + SO4 (aq)
This is a diprotic acid (2 ionizations)
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Lewis Acids and Bases
An atom, ion, or molecule that accepts
an electron pair to form a covalent
bond is a Lewis acid
An atom, ion, or molecule that donates
an electron pair to form a covalent
bond is a Lewis base
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Acid-base reactions
15-3 Objectives
• Describe a conjugate acid, conjugate base,
and amphoteric compound
• Explain the process of neutralization
• Explain how acid rain damages marble
surfaces
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Amphoteric
• A molecule or ion that can be classified as
an acid or a base.
• Ex
– HSO4-
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Conjugate Acids & Bases
The species that remains after a BrønstedLowry acid has given up a proton is the
conjugate base of that acid.
Example:
HF(aq)  H2O(l)  F- (aq)  H3O  (aq)
acid
conjugate
base
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Conjugate Acids & Bases
The species that is formed when a BrønstedLowry base gains a proton is the conjugate
acid of that base.
Example:
HF(aq)  H2O(l) 
base
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F- (aq)  H3O  (aq)
conjugate
acid
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Brønsted-Lowry acid-base reactions are
equilibrium systems (can occur both
forward and reverse) and involve two acidbase pairs known as conjugate acid-base
pairs.
HF(aq)  H2O(l) 
acid1
base 2
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F- (aq)  H3O  (aq)
base 1
acid2
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Strength of Conjugate Acids and Bases
The stronger the acid is the weaker its
conjugate base
The stronger the base, the weaker its
conjugate acid
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Neutralization Reactions
Are reactions between hydronium ions and
hydroxide ions to form water
Another product is a salt – a cation from an
acid and an anion from a base
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