202-NYB-05 Chapter 14 - Lecture

Chapter 14
202-NYB-05




14.1 How an Acid and Base is
Defined
• Arrhenius Model:
• Acids produce H+ ions in solution
• bases produce OH– ions.

• Brønsted–Lowry Model:
• Acids are proton (H+) donors
• bases are proton acceptors.doesn'thave basecouldbe anynegativeion
tohaveon anything canbeabase
HCl + H2O → Cl– + H3O+
acid base

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, 14.1
A conjugate Acid-Base
Pair ofthe result
nation

HA(aq) + H2O(l) H3O+(aq) + A–(aq)
o O 0
acid base conjugate conjugate
acid base

always1gpt
• Conjugate base is everything that remains of the acid molecule
after a proton is lost.

• Conjugate acid is formed when the proton is transferred to the
base.




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14.1




Brønsted
Brønsted
Acid Conjugate Acid Conjugate
Base
base

• Water acts as a base accepting a proton from the acid.

• Forms hydronium ion (H3O+).




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, 14.1
Acids and Bases
Unlike the Arrhenius definition of acids & bases, the
Brønsted-Lowry model is not limited to aqueous
solutions. ionic cpd
a
NH3(g) + HCl(g) NH4Cl(s)




Acid
Conjugate
Bas Conjugate base
e 5
acid


Ionic compound : Electrostatic charge attraction between two oppositely charged ions




14.1

Try one
Which of the following represent conjugate acid–base pairs?



a) HCl, HNO3

b) H3O+, OH–

c) H2SO4, SO42–
d) HCN, CN– move Ht


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, 14.1
Exercise
Aniline, C6H5NH2, was isolated in the 1800s and began
immediate use in the dye industry. What is the formula of
the conjugate acid of this base?

1. C6H5NH2+
2. C6H5NH3+ gainof Ht
3. C6H5NH–
4. C6H5NH+




7




14.2
Acids and Bases
Relative Acid Strength

inverse
always Weak
Strong Conjugate
Acid base
HA(aq) + H2O(l) H3O+(aq) + A-(aq)
For a strong acid,
this equilibrium lies
to the right.


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