Dr. Marwa Eid
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ACIDS
BASES
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WHAT IS AN ACID?


An acid is a solution that has an excess of H+
(hydrogen ion).
The more H+ ions, the more acidic the
solution.
COMMON ACIDS
Citric Acid
Vinegar
(acetic or ethanoic acid)
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SOME PROPERTIES OF ACIDS
 Produce H+ (as H3O+) ions in water (the hydronium ion is a
hydrogen ion attached to a water molecule)
 Taste sour
 Corrode metals
 Electrolytes
 React with bases to form a salt and water
 pH is less than 7
 Turns blue litmus paper to red “Blue to Red A-CID”
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LecturePLUS Timberlake
SOME COMMON ACIDS
HCl
hydrochloric acid
HNO3
nitric acid
H3PO4
phosphoric acid
H2SO4
sulfuric acid
CH3COOH
acetic acid
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




Acetic Acid = Vinegar
Citric Acid = lemons, limes, &
oranges.
It is in many sour candies such
as lemonhead & sour patch.
Ascorbic acid = Vitamin C
which your body needs to
function.
Sulfuric acid is used in the
production of fertilizers, steel,
paints, plastics & Car batteries
WHAT IS A BASE?
-A base is a solution
that has an excess
of OH- ions.
 -Another word for
base is alkali.
 -Your blood is a basic
solution.

COMMON BASES
Ammonia
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SOME PROPERTIES OF BASES

Produce OH- ions in water

Taste bitter, chalky

Electrolytes

Feel soapy

React with acids to form salts and water

pH greater than 7

Turns red litmus paper to blue
“Basic Blue”
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EXAMPLES OF BASES
Sodium Hydroxide
 Potassium Hydroxide
 Magnesium Hydroxide
 Ammonia

NaOH
KOH
Mg(OH)2
NH3
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
-Bases give soaps,
ammonia, and many
other
cleaning
products some of
their
useful
properties.
LecturePLUS Timberlake
LEARNING CHECK
Acid, Base Name
or Salt
CaCl2
______
_________________
KOH
______
_________________
Ba(OH)2
______
_________________
HBr
______
_________________
H2SO4
______
__________________
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LecturePLUS Timberlake
SOLUTION
cid, Base Name
orCaCl2
salt
KOH
calcium chloride
base
potassiuim hydroxide
Ba(OH)2
base
barium hydroxide
HBr
acid
hydrobromic acid
H2SO4
acid
sulfuric acid
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pH SCALE

•
pH is a measure of how acidic or basic a
solution is.
The pH scale ranges from 0 to 14.
•
Acidic solutions have pH values below 7
A solution with a pH of 0 is very acidic.
A solution with a pH of 7 is neutral.
Pure water has a pH of 7.
•
Basic solutions have pH values above 7.



pH Scale
ACID – BASE REACTIONS


A
reaction
between an acid
and a base is
called
neutralization.
An
acid-base
mixture is not as
acidic or basic as
the
individual
starting solutions.
ACIDS AND BASES
Acids:
 Arrhenius acid: Any substance that, when dissolved
in water, increases the concentration of hydronium
ion (H3O+)
 Bronsted-Lowry acid: A proton donor
 Lewis acid: An electron acceptor
Bases:
 Arrhenius base: Any substance that, when dissolved
in water, increases the concentration of hydroxide
ion (OH-)
 Bronsted-Lowery base: A proton acceptor
 Lewis base: An electron donor
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ARRHENIUS DEFINITION OF ACIDS AND
BASES
•

Arrhenius acid: Any substance that, when dissolved in
water, increases the concentration of hydronium ion
(H3O+)
Acids produce hydrogen ions (H+) in an
aqueous solution, while bases produce
hydroxide ion (OH-).
Acid: HCl (aq) Cl- (aq) + H+ (aq)
Base: NaOH(aq) Na+(aq) + OH-(aq)
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Acid/Base definitions
Definition 1: Arrhenius
Arrhenius acid is a substance that produces H+ (H3O+) in water
Arrhenius base is a substance that produces OH- in water
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4.3
ACIDS CAN HAVE MORE THAN ONE
IONIZABLE HYDROGEN.
Number of Ionizable
Hydrogens
Monoprotic
1
Diprotic
2
Triprotic
3
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One ionizable proton:
HCl → H+ + Cl Two ionizable protons:
Combined:
H2SO4 → H+ + HSO4+ + SO 2H
SO
→
2H
2
4
4
+
2HSO4 → H + SO4
 Three ionizable protons:
H3PO4 → H+ + H2PO4–
Combined:
H2PO4- → H+ + HPO42- H3PO4 → 3H+ + PO43HPO42- → H+ + PO4-3

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Bronsted Theory of Acids & Bases
Conjugate Acid-Base Pairs
An acid is a proton (H+) donor.
A base is a proton (H+) acceptor.
General Equation
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BRONSTED- LOWRY DEFINITION
OF ACIDS AND BASES

Example:
HF + H2O H3O+ + FAcid
Base
H3O+ : hydronium ion
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Lone Hydrogen ions do not exist by themselves in
solution. H+ is always bound to a water molecule
to form a hydronium ion
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CONJUGATE ACIDS AND BASES

General expression:
HA (aq) + H2O (l) H3O+ (aq) + A- (aq)
Acid
Base
Conjugate
Acid
Conjugate
Base
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CONJUGATE ACIDS AND BASES

Conjugate acid is the particle formed that has
received the proton. (ex: H3O+)

Conjugate base is the particle left from the acid
once it has donated the proton.
Note: Water acts as an acid and as a base. It is amphoteric.
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AMMONIA
NH3(aq) + H2O (l)  NH4 + (aq) + OH- (aq)
Base
Acid
Conjugate
Acid
Conjugate
Base
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LEWIS ACIDS AND BASES
An acid accepts a pair of electrons.
 A base donates a pair of electrons.


This is a more general definition than the
previous two.
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EXAMPLE OF A LEWIS ACID AND BASE
:NH3 + H+  NH4+
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THREE MODELS OF ACIDS AND BASES
Model
Definition of
Acid
Definition of
Base
Arrhenius
H+ producer
OH- producer
Bronsted-Lowry H+ donor
H+ acceptor
Lewis
Electron-pair
donor
Electron-pair
acceptor
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ELECTROLYTES
Electrolytes are species which conducts electricity when
dissolved in water.
Acids, Bases, and Salts are all electrolytes.
Salts and strong Acids or Bases form Strong
Electrolytes. They are fully dissociated , available to
conduct electricity.
HCl(s) + H2O  H3O+ + ClWeak Acids and Weak Bases form Weak Electrolytes.
Weak electrolytes have less ions available to conduct
electricity.
NH3 + H2O  NH4+ + OH34
Strong and Weak Acids/Bases
STRONG ACID: HNO3 (aq) + H2O (l)

H3O+ (aq) + NO3- (aq)
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Strong and Weak Acids/Bases

Weak acids are much less than 100% ionized in water.
*One of the best known is acetic acid = CH3CO2H and
ammonia
NH3 (aq) + H2O (l) ↔ NH4+ (aq) + OH- (aq)
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Strong and Weak Acids/Bases

Strong Base: 100% dissociated in water.
NaOH (aq)  Na+ (aq) + OH- (aq)
Other common strong
bases include KOH and
Ca(OH)2.
CaO (lime) + H2O -->
Ca(OH)2 (slaked lime)
Strong bases are the group I hydroxides
CaO
Calcium, strontium, and barium hydroxides are
strong, but only soluble in water to 0.01 M
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WEAK BASES
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ACIDS & BASES
STRONG
_ completely ionized
_ strong electrolyte
_ ionic/very polar bonds
bonds
Strong Acids:
HClO4
H2SO4
HI
HBr
HCl
HNO3
vs
WEAK
_ partially ionized
_ weak electrolyte
_ some covalent
Strong Bases:
LiOH
NaOH
KOH
Ca(OH)2
Sr(OH)2
Ba(OH)2
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