Acids and Bases

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Acids and Bases Lesson 1 Acid Base
Properties (Strong Weak acids)
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Properties of Bases
Neutralize acids
Are electrolytes that conduct electricity
Change litmus paper blue
Feel slippery
Taste bitter (baking soda)
Ex NaOH, Ca(OH)2, KOH, Zn(OH)2 -- notice they
all contain OH.
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Properties of Acids
Neutralize bases
Are electrolytes that conduct electricity
Change litmus paper red
Taste sour (vinegar, lemon juice)
React with metals such as Mg and Zn to make
H2 Mg(s) 2 HCl (aq) ? MgCl2 (aq) H2(g).
Ex HCl, HNO3, H2SO4 notice they all contain H.
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Salts

• A salt is the neutralization product when an acid
  and a base react to produce water.
• HCl NaOH ? NaCl H2O
• Notice, a salt does not contain H, or OH.

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• The Arrhenius Theory of Acids and Bases

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Arrhenius acid
produces H in solution
HCl ?
H Cl-
H is called a proton
produces OH- in solution
Arrhenius base
NaOH ? Na OH-
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• Bronsted-Lowry Theory of Acids and Bases

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Bronsted-Lowry Theory of Acids and Bases

• -more general theory
• -to accommodate reactions at equilibrium.
• -acids as proton donors
• -bases as proton acceptors

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Bronsted Acid
A proton donor
Chemistry 12
H3O Cl-
HCl H2O ?
strong
A proton acceptor
Bronsted Base
Chemistry 12
NH3 H2O ?
NH4 OH-
weak
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Write a Bronsted reaction for the base
HCO3-
weak
HCO3-
?
H2CO3 OH-
H2O
base
acid
acid
base
H2O and OH-
HCO3- and H2CO3
These are called Conjugate acid-base pairs They
differ by one proton H
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In Summary
1. Arrhenius bases dissociate in water to
produce OH-
2. Bronsted bases accept a proton from water to
produce OH-
3. Arrhenius acids dissociate in water to form H
4. Bronsted acids donate a proton to water to
form H3O
5. H is the same as H3O
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H is another way to show H3O.
H3O
H H2O
?
Hydronium ion
Proton

H
H2O
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• Conjugate acids and bases

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Conjugates

• A conjugate acid-base pair (conjugate pair) is a
  pair of chemical species which differ by only one
  proton (H)
• NH4, NH3
• A conjugate acid is the member of conjugate pair
  that HAS the extra proton.
• NH4
• A conjugate base is the member of the conjugate
  pair that LACKS the extra proton.
• NH3

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Conjugate Base
Conjugate Acid
One more H
1 less H
C6H5OH
C6H5O-
H gives a 1 Charge.
H2CO3
HCO3-
H2O
OH-
PO43-
HPO42-
HPO42-
H2PO4-
C6H5COOH
C6H5COO-
NH4
NH3
Fe(H2O)63
Fe(H2O)5(OH)2
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Acids and Bases Chart p334

• Relative Strengths of Bronsted-Lowry Acids and
  Bases
• Aqueous solutions at room temperature.

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Strong Acids
Weak Acids
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Strong Acids
Left side of Acid Chart -top six-
Completely ionize in water
Are good conductors.
Produce large amounts of H3O.
Have very large Kas, that is why you do not find
them on the chart.
Use a ? and not ? because it is not an
equilibrium situation.
HCl H2O ? H3O Cl-
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Weak Acids   Left side of the Acid Chart below
the top six. Do not completely ionize in
water. Are poor conductors. Produce small amounts
of H3O. Have small Kas, you will find Ka values
on the chart. Use a ? and not ? It means they
are Equilibrium situations! HF H2O ?
H3O F- Ka H3OF- 3.5 x
10-4 from page 334 HF Water is not
included because it is a pure liquid! Its
concentration is constant!
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You can also write  HF H2O ? H3O
F- HF H2O ? H F-  
HF- Ka 3.5 x 10-4
HF
We use H and H3O interchangeably. They mean the
same thing!
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Balance these neutralization equations

• H2SO4 NaOH
• HCl Sn(OH)4

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Homework Hebden Pg 110 1-2, Pg. 112 3-4