Chapter Outline
 8.1 Solutions and Their Concentrations
 8.2 Dilutions
Double-Displacement Reactions Again
Precipitation reactions in this section follow the same
pattern as acid-base reactions:
 8.3 Electrolytes and Nonelectrolytes
 8.4 Acids, Bases, and Neutralization Reactions
 8.5 Precipitation Reactions
 8.6 Oxidation-Reduction Reactions
 8.7 Titrations
AB + CD → AD + BC
 8.8 Ion Exchange
A Saturated Solution Example
Types of Solutions
 Saturated solution:
• Contains the maximum amount of solute that can
dissolve in a given volume at a given temperature.
• Solubility = g solute/100 mL solvent.
 Supersaturated solution:
• Contains more dissolved solute than predicted at a
given temperature.
Supersaturated Solution
Sodium acetate precipitates from a supersaturated solution.
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 Precipitate:
• Solid product formed from reactants in
solution.
• AgNO3(aq) + NaCl(aq) → NaNO3(aq) + AgCl(s)
 Can predict formation of precipitates
based on solubility “rules.”
We learned in Ch 4, p. 134, that the electrostatic energy (strength) of an ionic
bond depended on the charge squared over the distance between the ions
(radius of the ions). The solubility of ionic compounds generally follows the trend
that the greater the charge, and the smaller the radius, the more insoluble the
compound is.
𝐸=
Soluble
w/exceptions
cations
compounds
anions
compounds
solubility
+1
alkali metals
NH4+
-1
NO3CH3COO-
Always soluble
-2
SO42-
Soluble with exceptions
-2
S2-, O2-
Insoluble with
exceptions
-3
PO43-
Insoluble with
exceptions
+2
Al3+
+3
Table 8.3 - Solubility Guidelines
 Soluble Cations:
• Group I ions (alkali metals) and NH4+
 Soluble Anions:
• NO3− and CH3COO− (acetate)
• Halides (Group 17)
»
Exceptions: Cu+, Hg22+, Ag+, Pb2+
• Sulfates (SO42−)
»
Always
soluble
𝑄+ 𝑥 𝑄−
𝑑
Exceptions: Hg22+, Ag+, Pb2+, Ca2+, Ba2+, Sr2+
Ag+ Add to table
Insoluble
w/exceptions
Table 8.3 - Insoluble Compounds
 All hydroxides (OH−) except:
• Group IA = Li, Na etc
• Group IIA = Ca(OH)2, Sr(OH)2, and Ba(OH)2
 All sulfides (S2−) except:
• Group IA and NH4+
• All carbonates (CO32−) except IA, NH4+
 All phosphates (PO43−) except IA, NH4+
Add to table
2
Mnemonic device to help remember the insoluble
compounds -
Mnemonic device to help remember the
exceptions to the soluble compounds -
Shop for a chrome car
Cute HAPpy halides HAPpy sulfates "2"
Cl-, Br-, I-
Cu+
Ca2+
Sr2+
Hg22+
Ag+
u
l
f
i
d
e
s
Pb2+
Hg2
2+
Pb2+
Ba2+
y
d
r
o
x
i
d
e
s
x
i
d
e
s
h
o
s
p
h
a
t
e
s
S2OHO2-
Ag+
h
r
o
m
a
t
e
s
CrO42-
a
r
b
o
n
a
t
e
s
CO32-
PO43-
Applying the Solubility Rules – Will a
Precipitate Form?
Does a precipitate form when sodium chloride is
mixed with silver nitrate? If so, write the net ionic
equation for the formation of the precipitate:
NaCl → Na+ + Cl−
AgNO3 → Ag+ + NO3−
Net Ionic Equation
1. Write the balanced molecular equation.
2. Write the ionic equation showing the strong electrolytes completely
dissociated into cations and anions.
3. Cancel the spectator ions on both sides of the ionic equation
Formation of an Insoluble Product
NaI(aq) + Pb(NO3)2(aq) →
The soluble compounds break up
into ions and recombine -
K+(aq)
I-(aq)
Pb2+(aq)
NO3-(aq)
Sample Exercise 8.6
A precipitate forms when aqueous solutions of ammonium
sulfate and barium chloride are mixed. Write the net ionic
equation for the reaction.
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Sample Exercise 8.7 – Prediction the Mass of a Precipitate
Barium sulfate is used to enhance Xray imaging of the upper and lower GI tract. In
upper GI imaging, patients drink a suspension of solid barium sulfate in H2O. The
compound is not toxic because of its limited solubility. To make pure barium sulfate,
a precipitation reaction is employed: aqueous solutions of soluble barium nitrate and
sodium sulfate are mixed together, and solid barium sulfate is separated by filtration.
How many grams of barium sulfate (MW = 233.40) will be produced if exactly 1.00 L
of 1.55 M barium nitrate is reacted with excess sodium sulfate?
Sample Exercise 8.8 – Calculating Solute Concentration
from Mass of Precipitate
To determine the concentration of chloride ion in a 100.0 mL sample
of groundwater, a chemist adds a large enough volume of a solution
of AgNO3 to precipitate all the Cl- ions as silver chloride. The mass of
the resulting precipitate is 71.7 mg. What is the Cl - concentration in
the sample in mg/L?
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