Acids and Bases

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Acids and Bases
http//www.unit5.org/chemistry/AcidBase.html
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Acids
and
Bases
http//www.chalkbored.com/lessons/chemistry-11/aci
d-bronsted.ppt
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Properties
ACIDS
BASES

• electrolytes

• electrolytes

• sour taste

• bitter taste

• turn litmus red

• turn litmus blue

• react with metals to form H2 gas

• slippery feel

• vinegar, milk, soda, apples, citrus fruits

• ammonia, lye, antacid, baking soda

ChemASAP
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Acid vs. Base
Alike
Different
Different
Affects pH and litmus paper
pH gt 7
pH lt 7
Topic
Topic
bitter taste
sour taste
Related to H (proton) concentration
Acid
Base
does not react with metals
react with metals
pH pOH 14
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Common Acids and Bases
Strong Acids (strong electrolytes)
HCl hydrochloric acid HNO3 nitric
acid HClO4 perchloric acid H2SO4 sulfuric acid
Weak Base (weak electrolyte) NH4OH
ammonia
NH3 H2O ? NH4OH
Kotz, Purcell, Chemistry Chemical Reactivity
1991, page 145
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Common Acids

• Sulfuric Acid H2SO4
• Nitric Acid HNO3
• Phosphoric Acid H3PO4
• Hydrochloric Acid HCl
• Acetic Acid CH3COOH
• Carbonic Acid H2CO3

Battery acid
Used to make fertilizers and explosives
Food flavoring
Stomach acid
Vinegar
Carbonated water
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Common Bases
OH1-
hydroxide ion
Name Formula Common Name
Sodium hydroxide NaOH lye or caustic
soda Potassium hydroxide KOH lye or caustic
potash Magnesium hydroxide Mg(OH)2 milk of
magnesia Calcium hydroxide Ca(OH) 2 slaked
lime Ammonia water NH3 H2O household ammonia
.
NH4OH
NH41 OH1-
ammonium hydroxide
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Formation of Hydronium Ions
1
1




H
H2O
H3O
hydrogen ion
water
hydronium ion
(a proton)
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Arrhenius Acid
Any substance that releases H ions as the only
positive ion in the aqueous solution.
1-
1


Cl-
H3O
H2O
HCl
chloride ion
hydronium ion
water
hydrogen chloride
(an Arrhenius acid)
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Arrhenius Bases and Their Properties
According to the definition of Arrhenius a
Base - "a substance whose water solution
yields...
hydroxide ions (OH-) as the only negative ions."
YES
Are NaOH and NH3 considered to be Arrhenius bases?
1) Bases are electrolytes
Dissociation equation for NaOH
Dissociation equation for NH3
2) Bases cause indicators to turn a
characteristic color
3) Bases neutralize acids
4) Water solutions of bases tasted bitter and
feel slippery.
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Each of the following unbalanced equations
represents a reaction between a Arrhenius acid
and base. Identify those in each reaction
H2CO3 NH4OH ? (NH4)2CO3 H2O KOH H3PO4 ?
K3PO4 H2O HF NaOH ? NaF H2O Ba(OH)2
HNO2 ? Ba(NO2)2 H2O
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Brønsted-Lowry Acids and Bases
Acid any substance that donates a proton.
Base any substance that accepts a proton.
1-
1
d
d-

Cl-
H3O
H2O
HCl
chloride ion
hydronium ion
(base)
(acid)
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Brønsted-Lowry Acids and Bases
Acid any substance that donates a proton.
Base any substance that accepts a proton.
1-
1
d
d-

Cl-
H3O
H2O
HCl
chloride ion
hydronium ion
(base)
(acid)
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Brønsted-Lowry Acids and Bases
d
d-
H2O
NH3
(acid)
(base)
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Identify the Bronsted-Lowry acid and the
Bronsted-Lowry base in each reaction.

• NH4(aq) CN- (aq) ? HCN (aq) NH3 (aq)
• (CH3)3N(aq) H2O ? (CH3)3NH(aq) OH-(aq)
• HCHO2(aq) PO43- ? CHO2-(aq) HPO42-(aq)
• HSO4-(aq) CO32- ? SO42- (aq) HCO3-(aq)

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Definitions

• Lewis

• Acids are electron pair acceptors.
• Bases are electron pair donors.

Lewis base
Lewis acid
Courtesy Christy Johannesson www.nisd.net/communic
ationsarts/pages/chem
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Acid Definitions
Arrhenius acids
Arrhenius Acids and Bases Acids release hydrogen
ions in water. Bases release hydroxide ions in
water. An acid is a substance that produces
hydronium ions, H3O, when dissolved in water.
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Acid Definitions
Lewis acids
The Arrhenius model of acids and bases was
broadened by the Brønsted-Lowry model. The Lewis
acid-base model is the most general in scope.
The Lewis definition of an acid includes any
substance that is an electron pair acceptor a
Lewis base is any substance that can act as an
electron pair donor.
Brønsted-Lowry
Arrhenius acids
Ralph A. Burns, Fundamentals of Chemistry 1999,
page 483
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Acid Definitions
Lewis acids
The Arrhenius model of acids and bases was
broadened by the Brønsted-Lowry model. The Lewis
acid-base model is the most general in scope.
The Lewis definition of an acid includes any
substance that is an electron pair acceptor a
Lewis base is any substance that can act as an
electron pair donor.
Brønsted-Lowry
Arrhenius acids
Ralph A. Burns, Fundamentals of Chemistry 1999,
page 483
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Acid Base Systems
Type Acid Base
Arrhenius H or H3O producer OH - producer
Brønsted- Lowry Proton (H ) donor Proton (H ) acceptor
Lewis Electron-pair acceptor Electron-pair donor