Salts

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Drill: Calculate the
pH of 0.10 M H2Z in
0.50 M KHZ.
-5
Ka1 = 2.0 x 10
-9
Ka2 = 5.0 x 10
Salt or
Hydrolysis
Reactions
Hydrolysis
Any reaction in which water
is decomposed with all or
part of its decomposition
portions combining with the
products
Hydrolysis
Water is added to
decompose
something
Hydrolysis
MX + HOH
HX + MOH
Salts
Salts
•Ionic compounds
that dissolve ~
100 % in water
Salts of Acids
•Salts of acids are
negative
(A )
Salts of Bases
•Salts of bases are
Positive
+
+
(M or B )
Salt Solutions
•When salts dissolve,
their ions can
recombine with water
Salt Solutions
•The salts of weak
acids can recombine
with water producing
basic solutions
Salt Solutions
•The salts of weak
bases can recombine
with water producing
acidic solutions
Salt Solutions
A
+
B
+ H2O
HA +
+ H 2O
+
H
OH
+ BOH
Drill: Calculate the
salt/acid ratio of a
solution of benzoic acid
& sodium benzoate at a
pH of 5.00.
-5
Ka HBz = 6.4 x 10
Salt or
Hydrolysis
Problems
Salt Problem
•Calculate the pH of
a 0.20 M solution
of NaBz
-5
•Ka HBz = 6.4 x 10
Drill: Calculate the
pH of a solution of
0.10 M NH3 in 0.20
NH4Cl.
-5
Kb NH3 = 1.8 x 10
Salt or
Hydrolysis
Problems
Salt Problem
•Calculate the pH of
a 0.20 M solution
of KNO2
-4
•Ka HNO2 = 7.1 x 10
Salt Problem
•Calculate the pH of a
0.10 M solution of
R-NH3Cl
-5
•Kb R-NH2 = 2.5 x 10
Calculate the pH of
a 0.18 M solution
of KC2H3O2
-5
•Ka = 1.8 x 10
Drill: Calculate the salt
to acid ratio required to
make a buffer solution
with a pH of 4.495
using benzoic acid.
-5
Ka HBz = 6.4 x 10
Salt Applications
•Salts of strong acids
& weak bases make
acidic solutions
Salt Applications
•Salts of strong bases
& weak acids make
basic solutions
Salt Applications
•Salts of strong acids
& strong bases make
neutral solutions
Predict Relative pH
•NaAc
•KNO3
•KHSO4
MnCl2
NH4Br
NH4Ac
Predict Relative pH
•KAc
•KClO2
•K2SO4
NaCl
NH4Cl
NaI
Anhydrides
•Compounds without
water; that when
added to water, form
other compounds
Acid Anhydrides
•Non-metal oxides
that form acids when
added to water
Basic Anhydrides
•Metal oxides that
form bases when
added to water
Predict Relative pH
•Na2O
SO2
•NO2
CO2
•CaO
Al2O3
Calculate the pH of
a 0.16 M solution
of KC7H5O2
-5
•Ka = 6.4 x 10
•Calculate the pH
of a solution of
0.0030 M KQ.
-5
•Ka HQ = 3.0 x 10
Drill: Calculate the
pH of a 0.72 M
NH4NO3 solution.
-5
Kb NH3 = 1.8 x 10
Are there any
questions on
previous
material?
A/B eq, Buffer
& Salt
Hydrolysis
Problem
-1],
Calculate [H3PO4], [H2PO4
-2
-3
+
+
[HPO4 ], [PO4 ], [K ], [H ],
& pH of 1.0 M KH2PO4 in
0.50 M K2HPO4.
-3
Ka1 = 7.5 x 10
-8
Ka2 = 6.2 x 10
-13
Ka3 = 4.2 x 10
You need to make a buffer
solution with its greatest
buffering capacity at pH ~
5.4. In general terms,
describe what acid or base
you would chose, & how
you would make the buffer.
11.2 g of KOH was added
to 2.0 L of 0.075 M
H2CO3. Calculate the
molarity of all ions
present in the solution.
-7
Ka1 = 4.4 x 10
-11
Ka2 = 4.8 x 10
Drill: Calculate
the pH of
0.10 M HF.
-4
Ka HF = 6.5 x 10
Test
Review
Expect a straight
acid/base
problem like the
drill
Calculate the pH
of 0.10 M HF in
0.20 M KF.
-4
Ka HF = 6.5 x 10
Calculate the pH
of 0.10 M KF.
-4
Ka HF = 6.5 x 10
Predict Relative pH
K2O
ClO2
SO3
MgO
(NH4)2O
N2O3
Predict Relative pH
•KAc
•KClO2
•K2SO4
NaCl
NH4Cl
NaI
Calculate the pH
of 5.0 M KCN.
-10
KaHCN= 5.0 x 10
Calculate pH of:
0.20 M MOH in
0.50 M MCl
-5
Kb = 5.0 x 10
Calculate pH of:
0.20 M MCl
-5
Kb = 5.0 x 10
Drill: Calculate
the pH of
0.20 M KQ.
-5
Ka HQ = 8.0 x 10
Calculate pH of:
•0.20 M HNO2
-4
•Ka = 2.0 x 10
Calculate pH of:
•3.0 M HZ in
2.0 M KZ
•Ka HZ = 3.0 x
-5
10
Calculate pH of:
•0.20 M KR
-5
•Ka HR = 2.0 x 10
Calculate pH of:
•2.0 M HQ
-6
•Ka = 2.0 x 10
Calculate pH of:
•0.60 M HZ in
0.90 M KZ
•Ka HZ = 3.0 x
-5
10
Calculate pH of:
•0.20 M KQ
-7
•Ka HQ = 2.0 x 10
1.5 L of 0.25 M Ba(OH)2 was
added to 1.0 L of 0.60 M
H2SO3. Calculate [H2SO3],
-2
+
[HSO3 ], [SO3 ], [H ], [OH ],
& pH of the solution.
-2
Ka1 = 1.7 x 10
-8
Ka2 = 6.0 x 10
Review of Acid/Base
descriptions and
Acid/Base, Buffer, &
Salt Equilibria
Arhenius, BronstedLowry, & Lewis
Acids & Bases
Strong Acids
Strong Bases
Acid rxns
Base rxns
A/B Equilibrium
Constants
KW, KA, KB, & pH
Calculate pH of:
•0.025 M HNO3
•0.020 M KOH
150 mL of 0.10 M KOH was
added to 100.0 mL of 0.10 M
H2CO3. Calculate [H2CO3],
-2
+
[HCO3 ], [CO3 ], [H ], [OH ],
& pH of the solution.
-7
Ka1 = 4.4 x 10
-11
Ka2 = 4.7 x 10
-1
A ],
Calculate [H3A], [H2
-2
-3
+
+
[HA ], [A ], [K ], [H ],
[OH ], & pH of
2.0 M KH2A.
-3
Ka1 = 4.0 x 10
-8
Ka2 = 5.0 x 10
-13
Ka3 = 2.5 x 10
The take-home
portion of the
test is due by
8:15 tomorrow
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