Acids and Bases

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Acids and Bases
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• Acids and bases only form when dissolved in water
  to form a solution!
• HCl (g) hydrogen chloride gas
• HCl (aq) hydrogen chloride gas
  dissolved in water the new name is
  hydrochloric acid

HCl
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Acid/Base Theories
Acids Compounds containing hydrogen that
ionize to yield hydrogen ions in an aqueous
solution Base Compounds that ionize to yield
hydroxide in an aqueous solution
Arrhenius
Acids A hydrogen ion donor Bases A hydrogen
ion acceptor
Brownsted-Lowry
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Arrhenius looked at the substances which were
called acids. Some of these substances were known
from even before the days of alchemy.
They taste sour, turn blue litmus to red,
neutralize bases, release hydrogen gas when added
to an active metal and release carbon dioxide
when added to a carbonate.
Arrhenius said these properties were due to the
production of H ions when acids dissolve in
water.
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Acids and Bases

• Acids have hydrogen (H) or
• hydronium (H3O) ions in solution
• 2. Bases have hydroxide (OH-) and metallic ions
  in solution must be OH TOGETHER!
• Alkaline is a term that refers to a base.

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Identify each as an acid or base according to
Arrhenius

• HCl
• 2. H3PO4
• 3. NaOH
• 4. Ca(OH)2

acid
acid
OH not together
base
base
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Acids and Bases

• 1. Acids are hydrogen donors
• ? they form a conjugate base in reactions
• Conjugate means to be related to or formed from
• 2. Bases are hydrogen acceptors
• ? they form a conjugate acids in reactions

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Identify acid, base, conjugate acid and conjugate
base.
conj. acid
base
?
HF H2O ? H3O F-
acid
conj. base
conjugates always on this side
ALWAYS LOOK TO SEE HOW THE REACTANTS CHANGED!
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Example 2
?

• H2SO3 H2O ? HSO3- H3O

CONJUGATE BASE
ACID donates hydrogen
BASE accepts hydrogen
CONJUGATE ACID
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Example 3

• H2PO4 H2O ? H3PO4 OH-

CONJUGATE BASE
ACID donates hydrogen
BASE accepts hydrogen
CONJUGATE ACID
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PHYSICAL Properties of Acids

• sour taste
• can burn
• soluble in water
• conductive (electrolyte)
• pH 0-6.9 (more H than OH-)

0
14
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INCREASING ACIDITY
INCREASING BASICITY
NEUTRAL
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PHYSICAL Properties of Bases

• bitter taste
• can burn
• soluble in water
• conductive (electrolyte)
• dissolves fats and oils
• slippery
• pH 7.1-14 (more OH- than H)

0
14
7
INCREASING ACIDITY
INCREASING ALKALINITY
NEUTRAL
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CHEMICAL Properties of Acids

• react with (corrode) metals
• react with bases
• reacts with carbonates (limestone)

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CHEMICAL Properties of Bases

• react with acids

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ACIDS
BASES

• vinegar, milk, soda, aspirin, citrus fruits

• ammonia, lye, antacid, baking soda

Neutral Substances

• pH 7
• Equal H OH-
• pure water

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Indicators

• Indicators are dyes.
• Indicators are qualitative because they show
  acidity or alkalinity by changing color.

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Litmus Paper

• Acids turn red litmus paper red.
• Acids turn blue litmus paper red.
• Bases turn red litmus paper blue.
• Bases turn blue litmus paper blue.
• If red litmus stays red and blue litmus stays
  blue, the substance is neutral!

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pH scale- measure of hydrogen ion concentration.
It spans from 0 to 14.
Neutral
Weak Acid
Strong Acids
Strong Base
Weak Base

• Strong Acid acids that ionize completely (
  produce maximum of ions.) Are good conductors
  of electricity.
• Examples Nitric Acid, Sulfuric Acid
• Weak Acids ionize only partially
• Examples Acetic acid, boric acid
• Strong Base breakdown completely into metal ions
  and hydroxide ions

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pH paper

• Acids turn pH paper RED to ORANGE.
• Bases turn pH paper BLUE to PURPLE.
• Neutral substances turn pH paper GREEN.

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• Acids and bases are solutes that dissolve in
  water.
• During dissolving, the acid or base must undergo
  hydration and dissociation.
• Acids and bases ionize in water to produce
  electrolytes which are ions that can conduct an
  electric current.
• A conductivity apparatus is a piece
  of equipment used to measure
  whether electrolytes are present in the
  solution.

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poor conductor (light bulb dimly lit)
highly conductive (light bulb VERY bright)
electrolytes are
electrolytes are
ions
ions
dissociates partially (lt100) weak acid animation
dissociates 100 strong acid animation
The lower the Ka the weaker the acid b/c fewer
ions are in solution.
No Ka value b/c dissociation is 100.
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Strong Acids
Hydrobromic acid HBr Hydrochloric acid
HCl Hydroiodic acid HI Nitric acid
HNO3 Perchloric acid HClO4 Sulfuric acid
H2SO4
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poor conductor (light bulb dimly lit)
highly conductive (light bulb VERY bright)
electrolytes are -
electrolytes are -
ions
ions
dissociates partially (lt100)
dissociates 100
The lower the Kb the weaker the base b/c fewer
ions are in solution.
No Kb value b/c dissociation is 100.
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Strong Bases
LiOH lithium hydroxide NaOH sodium
hydroxide KOH potassium hydroxide RbOH rubidi
um hydroxide CsOH cesium hydroxide Ca(OH)2 ca
lcium hydroxide Sr(OH)2 strontium
hydroxide Ba(OH)2 barium hydroxide
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Neutralization when acids and bases react with
each other

• General reaction
• acid base water salt
• The characteristic properties of both reactants
  are destroyed.

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Acid- Base NeutralizationDouble Displacement
Reactions
acid base salt water
KNO3 H2O
HNO3 KOH
HF NaOH
NaF H2O
HCl Ca(OH)2
CaCl2 H2O
2
2