Chapter 15
Section 1 What are Acids and
Bases?
Cycle 6 Chemistry II Lesson 3
Identify and distinguish „conjugate acids‟ and
„conjugate bases‟
WARMUP:
Complete the reaction NH3 + HCl → _____ + ____
HINT: NH3 is a base so it can accept a H+
HCl is an acid so it can donate a H+
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Chapter 15
Section 1 What are Acids and
Bases?
Cycle 6 Chemistry II Lesson 3
Identify and distinguish „conjugate acids‟ and
„conjugate bases‟
AGENDA:
VOCAB: “Conjugate Acid”, “Conjugate Base”
CLASSWORK: Get out Bronsted-Acid/Base
worksheet. On right-hand side of equations, mark
the Conjugate Acid and Conjugate Base.
HOMEWORK: Conjugate Pairs WS
[HONORS]:
Strong-Weak Conjugates WS
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Chapter 15
Visual Concepts
Brønsted-Lowry Acids and Bases
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Chapter 15
Section 1 What Are Acids and
Bases?
Brønsted-Lowry Classification, continued
Conjugate Acids and Bases, continued
• Look again at the equation for the reversible reaction
of ammonia, NH3, with water:



NH3 (aq )  H2O(l ) 
NH
(
aq
)

OH
(aq )

4
base
acid
• Water donates a proton to ammonia, so it is an acid.
• Ammonia accepts the proton, so it is a base.
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Chapter 15
Section 1 What Are Acids and
Bases?
Brønsted-Lowry Classification, continued
Conjugate Acids and Bases, continued
• When the reaction is reversed, we can identify
another acid and another base.

 NH3 (aq )  H2O(l )
NH4 (aq )  OH- (aq ) 

acid
base
• In this reaction, the ammonium ion donates a proton
to the hydroxide ion.
• NH4+ is the acid, and OH− is the base.
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Chapter 15
Section 1 What Are Acids and
Bases?
Brønsted-Lowry Classification, continued
Conjugate Acids and Bases, continued
• The ammonium ion is called the conjugate acid of
the base, ammonia.
• A conjugate acid is an acid that forms when a
base gains a proton.
• The hydroxide ion is called the conjugate base of the
acid, water.
• A conjugate base is a base that forms when an
acid loses a proton.



NH3 (aq )  H2O(l ) 
NH
(
aq
)

OH
(aq )

4
base
acid
conjugate acid conjugate base
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Chapter 15
Visual Concepts
Conjugate Acids and Bases
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Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 15
Section 1 What Are Acids and
Bases?
Brønsted-Lowry Classification, continued
Conjugate Acid-Base Pairs
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