Equilibrium
1. Molecular ------------------- Chapter 15
2. Ionic (Weak Acid / Base ) - Chapter 16
3. Ionic (“Insoluble” Salts) - Chapter 17
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HCl(aq) is a strong acid but Cl- is a “weak” base. Why? Because Cl- will not react with H+. Why Not? If it did, HCl(aq) {a strong acid} would form.
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Equilibrium
1.^
Molecular
------------------- Chapter 15
2.^
Ionic (Weak Acid / Base ) - Chapter 16
3.^
Ionic (“Insoluble” Salts)
- Chapter 17
STRONG
Acids & Bases
1.^
COMPLETELY IONIZED
1.^
COMPLETELY IONIZED
1.^
COMPLETELY IONIZED
1.^
COMPLETELY IONIZED (a)^
HCl(aq)
^
+^ H (aq)
+
Cl
-^ (aq)
(b)^
NaOH(aq)
^
+Na (aq) + OH
- (aq) 2.^
ONLY IONS PRESENT
2.^
ONLY IONS PRESENT
2.^
ONLY IONS PRESENT
2.^
ONLY IONS PRESENT + (a) H
(aq) & Cl
-^ (aq)
(b)^
+Na (aq) & OH
- (aq)
3.^
NO EQUILIBRIUM
3.^
NO EQUILIBRIUM
3.^
NO EQUILIBRIUM
3.^
NO EQUILIBRIUM
The [H] of 0.
M^
HCN(aq) is?
{K
= 4.9 x 10a
What do you do 1
st^?
ST 1
Write & Balance “Reaction” HCN(aq)
+ H
(aq) + CN
-^ (aq)
nd^2 Write Equilibrium Expression
]
[
]
][
[H
CN HCN
Ka
−
Initial
Change
Equilibrium
Find [H] of 0.
M^
HCN
K= 4.9 x 10a^
HCN(aq)
+ H
(aq) + CN
-^ (aq)
I^ NITIALNITIALNITIALNITIAL
C^ HANGEHANGEHANGEHANGE
-^
x^
+^ x
+^ x
E^ QUILIBRIUMQUILIBRIUMQUILIBRIUMQUILIBRIUM
0.5 – x
x + 0
x + 0
What approximation?
Yes!!Why?
Since
x^ ≅
1.6 x 10
-^
is so small
0.50 - x
x 0.5x = 0.
x 0.
2 2
pH – A measure of Acidity
The pH of a solution is defined as
the
negative logarithm of the hydrogen ion
concentration (in mol/L)
.
pH = –log [H
+]
pOH = –log [OH
- ]
pH + pOH = 14
Definitions of Acids & Bases
- Arrhenius2. Bronsted-Lowry3. Lewis
Acid / Base
ACIDACIDACIDACID
:^ A substance which dissociates to form hydronium ions (H
+O 3
) in solution :
HA(
aq )
+ H
( aq
) + A
- ( aq
BASEBASEBASEBASE
:^ A substance that dissociates to form hydroxide ions (OH
- ) in solution :
MOH(
aq )
+ M
( aq
) + OH
- ( aq
M = a Metal
LEWISLEWISLEWIS
Acid / Base
-^ Acid
is an
electron-pair acceptor
.^ These are
generally cations and neutral molecules withvacant valence orbitals. For example H
+^ & BF
. 3 -^ Base
is an
electron-pair donor
. These are
generally anions and neutral molecules withavailable pairs of electrons, such as H
O, NH 2
, O 3 2–
-^ The bond formed is called a
coordinate bond
STRENGTH OF ACIDS AND BASESSTRENGTH OF ACIDS AND BASESSTRENGTH OF ACIDS AND BASES HCl(aq) is a strong acid but Cl
-^ is a “weak” base
Why?
Because Cl
-^ will not react with H
Why Not?
If it did, HCl(aq) {a strong acid} would form
which does not exist
STRENGTH OF ACIDS AND BASESSTRENGTH OF ACIDS AND BASESSTRENGTH OF ACIDS AND BASES HClO
4 HI HBrHClHNO
3
HFHNO
2 HCOOHNH
- 4 HCNHO^2
ClO
- 4
I Br^
Cl^
NO
- 3
– F NO
- 2 HCOO
NH
3 CN
- OH
ACID
BASE
ACID
BASE
Increasing Acid Strength
Strong Acids
- BASE PAIRS
An Acid and a Base thatdiffer only in the presence^ {or absence}
of a proton.
- BASE PAIRS
HClO
4 HI HBrHClHSO^2
4 HNO
3 HO^3
HSO
- 4
HSO
- 4 HFHNO
2 HCOOHNH
- 4 HCNHO^2 NH
3
ClO
- 4
- I – Br^ – Cl^ HSO
- 4 NO
- I – Br^ – Cl^ HSO
- 3 HO^2 SO
2– 4
SO
2– 4
- F (^) NO
- 2 HCOO
NH
3 CN
- OH
NH
- 2
ACID
CONJ. BASE
ACID
CONJ. BASE
What are the conjugate bases of the following
Brønsted–Lowry acids
HSO^2
4 HClO
4 HSO^2
4 HSO
– 4 HO 2
+ H
O^2
^
HO^3
+^ + HSO
- 4