Diapositive 1

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Chemistry B11
Chapter 9 Acids and Bases
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Acids and Bases
Acids sour
Bases bitter or salty
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Acids and Bases
Arrhenius definition
Acid produces H3O
CH3COOH(aq) H2O(l) CH3COO-(aq)
H3O(aq)
H3O (Hydronium ion)
H(aq) H2O(l) H3O(aq)
Base produces OH-
H2O
NaOH(s) Na(aq) OH-(aq)
NH3(aq) H2O(l) NH4(aq) OH-(aq)
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Acids and Bases
Bronsted and Lowry definition
Acid donates H (proton)
Base accepts H (proton)
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Acids and Bases
HCl H2O Cl- H3O
acid
base
Conjugate base
Conjugate acid
Conjugate acid-base pair
Conjugate acid-base pair
C6H5OH H2O C6H5O- H3O
acid
base
Conjugate base
Conjugate acid
Conjugate acid-base pair
Conjugate acid-base pair
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Acids and Bases
Weak acid and base is partially ionized in
aqueous solution.
produces less H and OH-
CH3COOH(aq) H2O(l) CH3COO-(aq) H3O(aq)
NH3(aq) H2O(l) NH4(aq) OH-(aq)
Strong acid and base is completely ionized in
aqueous solution.
produces more H and OH-
HCl(aq) H2O(l) Cl-(aq) H3O(aq)
NaOH(aq) H2O(l) Na(aq) OH-(aq)
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Acids and Bases
Monoprotic acids HCl
Diprotic acids H2SO4
Triprotic acids H3PO4
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Naming binary acids
HF
F- flouride ion Hydroflouric acid
HCl
Cl- chloride ion Hydrochloric acid
H2S
S2- sulfuride ion Hydrosulfuric acid
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Naming ternary acids
-ite ion
-ous acid
Anion
-ate ion
-ic acid
HNO2
NO2- Nitrite ion Nitrous acid
HNO3
NO3- Nitrate ion Nitric acid
H2CO3
CO32- carbonate ion carbonic acid
H2SO3
SO32- sulfurite ion sulfurous acid
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Ionization constant
HA H2O A- H3O
A- H3O
K
not for strong acids
Equilibrium constant
HA H2O
- Log Ka pKa
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pH and pOH
H2O H2O OH- H3O
KW H3O OH- (110-7) (110-7)
H3O OH- 110-14
pH pOH 14
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pH and pOH
pH - log H3O or -log H
pOH - log OH-
pH scale
0
7
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Base
Neutral
Acid
H3O ?
H3O ? and OH- ?
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pH meter and pH indicators
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Acid Reactions
1. Reaction with metals (strong acids) produces
H2 and a salt.
Mg(s) 2HCl(aq) MgCl2(aq) H2(g)
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Acid Reactions
3. Neutralization between an acid and a
base. produces a salt and water
KOH(aq) 2HCl(aq) KCl(aq) H2O(l)
2NaOH(aq) H2SO4(aq) Na2SO4(aq) 2H2O(l)
Strong acids react with strong bases. Weak acids
react with weak bases.
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Titration (Neutralization reaction)
MB known VB known
MA unknown VA known
Equivalence point equal amount of acid (H)
and base (OH-) (pH 7).
2NaOH 1H2SO4 ? 2NaSO4 2H2O
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Buffers
acid or base
pH stays constant
Buffer
Equal molar amount of a weak acid and a salt of
weak acid. Equal molar amount of a weak acid and
its conjugate base.
1 mole CH3COOH 1 mole CH3COONa 1 mole CH3COOH
1 mole CH3COO-
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Buffers
pH of blood 7.4
Carbonate buffer H2CO3 / HCO3-
Phosphate buffer H2PO4- / HPO42-
Proteins buffer
H2CO3 OH- ? HCO3- H2O HCO3- H3O ? H2CO3
H2O
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Buffers
If AH (weak acid) A- (conjugate base)
pH of buffer pKa of weak acid