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Accelerated Chemistry
Chapter 13
Accelerated Chemistry Chapter 13 notes
Chapter 13 Review: 4, 8-12, 20, 22, 23, 27, 28, 29, 30, 34, 39
13.1 Compounds in Aqueous Solution
A. Aqueous solution = A solution in which
1. Example: A solution of water (the
is the solvent (
) and NaCl (the
).
)
2. Aqueous solutions can be electrolytes or non electrolytes.
a. Electrolytes and non-electrolytes are solutes of
solutions.
b. Do electrolytes conduct electricity?
c. Are non-electrolytes conductors?
d. Are all electrolytes conductors?
e. Are all conductors electrolytes?
CONDUCTORS
Pure Substance
Mixtures
Elements
Compounds
Alloys
Electrolytic Sol’n
All metals: Cu, Ag,
Fe
All ionic
compounds in
liquid state: NaBr
(I), KNO3 (I)
Stainless steel,
Sterling silver
Water solutions of
NaBr,HCl, NH3
(aqueous solution)
NONCONDUCTORS
Pure Substance
Mixtures
Elements
Compounds
Non-electrolytic Sol’n
All nonmetals: I2,
P4
All covalent compounds in
liquid state: HBr (I), Al2Cl6 (I),
Water solutions of sucrose,
isopropyl alcohol, ethyl alcohol,
glycerin
(aqueous solutions)
All solid compounds: Sucrose,
NaBr (s), AlBr (s)
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Accelerated Chemistry
Chapter 13
B. Theory of Ionization
Theory of Ionization - Some water solutions conduct
solutions are called
molecules by the action of the
. These
from solute
. The formation of
.
Strong electrolytes:
NaCl(s)
HCl(g)
+
+

H2O(l)

H2O(l)
Weak electrolyte:
HC2H3O2(l)
+

H2O(l)
A
arrow shows a strong electrolyte fully producing
indicates that the weak electrolyte does not fully
. A
yield sign
.
In 1887, Svante Arrhenius (Sweden) proposed the theory of
Some substances
of changes in
.
He based his ideas on observations
points with different molal concentrations
and
Note: Some reactions get a
arrow (
) and some get a
Arrhenius proposed that when some chemicals are dissolved in
particles with
.
arrow (
, they produce
ionic compounds
NaCl(s) +
MgCl2(s) +
acids

H2O
H2O 
(covalent dissociation)
HCl(g)
H2SO4(g)
+
H2O
+
H2O
Substances that are not
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

,
, or
do not dissociate/ionize.
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).
Accelerated Chemistry
Chapter 13
C. Dissociation
The separation of ions that occurs when an ionic compound dissolves.
1. A 1.0 M solution of sodium chloride contains:
1 mole of Na+ ions and 1 mole of Cl- ions.
NaCl(s)
H2O
--------->
1 mole
2. A 1.0 M solution of calcium chloride contains:
1 mole of Ca+2 ions and 2 moles of Cl- ions – a total of 3 moles of ions.
CaCl2(s)
H2O
--------->
1 mole
3. (a) Dissolve Al2(SO4)3 in water. (b) How many moles of aluminum ions and sulfate
ions are produced by dissolving 1 mol of Al2(SO4)3. (c) What is the total number of
moles of ions produced by dissolving 1 mol of Al2(SO4)3?
(a) Al2(SO4)3(s)
H2O
--------->
(b) 1 mole
--------->
(c) 2 moles Al3+ + 3moles SO42-
=
of solute ions
D. Solubility Equilibria:
No ionic compound has
No ionic compound has
solubility.
solubililty.
Rough rules of solubililty (using the solubility tables):
a. If more than 1 gram per 100g H20 before saturation =
b. If .1 gram to 1 gram per 100g H20 =
c. If less than .1 gram per 100g H20 =
1. Very slightly soluble ionic compounds – when placed in water, an equilibrium is
established between the solid compound and its ions in solution:
Example:
AgCl(s)
Fe(OH)3(s)
Ag2S(s)
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Accelerated Chemistry
Chapter 13
2. Precipitation Reactions = Soluble compounds form
Type of rxn:
products.
- remember – reactants are soluble in water
3. Net ionic equations – double replacement reactions and other reactions of ions in
aqueous solutions are represented as ‘net ionic equations.’
Steps:
1. write an equation (molecular equation)
2. write total ionic equation
3. write a net ionic equation – only those compounds and ions that undergo a chemical
change in a reaction in an aqueous sol’n and does not include spectator ions (ions
found on the reactants and products side).
Ex1: Potassium Chloride + Silver nitrate
Molecular Equation:
Total Ionic Equation:
Net Equation:
Ex2:
Molecular Equation:
Total Ionic Equation:
Net Equation:
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Accelerated Chemistry
Chapter 13
15.2 Colligative Properties of Solution
Molecular Electrolytes
A. Molecular solutes can form electrolytic solutions if they are highly polar.
Ionization versus dissociation
1. Dissociation = The separation of
that occurs
2. Ionization = The formation of
that occurs when a
compound
dissolves in water (water rips aparts molecules and turns them into ions
Ionization example:
H2O + HCl 
When a hydrogen chloride molecule ionizes in water, its hydrogen ion bonds covalently
to a water molecule. A
ion and a
ion are formed.
Hydronium Ion:
The H+ ion attracts other molecules or ions so strongly that it does not normally exist, so
the H+ ion becomes covalently bonded to oxygen.
Substances which form electrolytic solutions are:
Acids
HX
HCl, HNO3
Bases
MOH
NaOH
Salts
MX
NaCl, KBr, CaCO3
H = Hydrogen
M = Metal
OH = Hydroxide
X = NM or P-ion
Why?
Which of the following form electrolytic solutions?
MgBr2
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C8H18
KOH
C12H22O11
HNO3
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Accelerated Chemistry
Chapter 13
Strong vs. weak electrolytes
Some compounds ionize/dissociate completely, while others don’t. (
Strong electrolyte – a compound that when dissolved/ionized, yields
)
% ions.
Distinguishing factor of strong electrolytes – to whatever extent they dissolve in
water, they yield only
: HCl, HBr and HI are 100% ionized in dilute aqueous
solutions.
Weak electrolyte – a solute that yields a relatively
concentration of ions in an
aqueous solution.
HF(aq) + H2O(l)
In an aqueous solution, the majority of HF molecules are present as dissolved
HF
s.
In general, the extent to which a solute ionizes in solution depends on the bonds within
the molecules of the
and the strength of attraction to
molecules.
Note: If the strength of bonds in
molecules < the attractive forces of the
dipoles, then the covalent bonds break and the molecule separates into
.
Properties of Electrolyte Solutions
Conductivity of Solutions
To compare the conductivities of strong and weak electrolytes, the conductivities of
solutions of equal concentration must be compared.
Ionization of pure water:
H2O(l) + H2O(l)
So why does water that comes out of the tap conduct electricity?
It contains a high enough concentration of dissolved
conductor than pure water.
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to make it a better
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Accelerated Chemistry
Chapter 13
Colligative Properties of Electrolytic Solutions
Properties that depend on the concentration of the solute particles. Freezing point and
boiling point are
properties.
Freezing point depression – the difference between the freezing points of a pure
solvent and a nonelectrolyte solution in it.
Solutions that conduct electricity contain
Ionic compounds
:
NaCl(s) +
H2O(l) yields
MgCl2(s) +
H2O(l) yields
Acids
.
(dissociation of a covalent compound):
HCl(g)
+
H2O(l)
yields
H2SO4(l) +
H2O(l)
yields
Substances that are not acids, bases, and salts do not
When solutes dissolve in liquids, they
.
the freezing point.
Two factors affect the degree of change in the temperature: the amount of the
and the nature of the
.
∆tf = kf (m)(x)
x = # of
produced when the solute dissolves
kf water = -1.86 oC/m
As the number of solute particles increase, the freezing point
.
Ex1: Calculate the freezing point of 10.00 grams of NaCl in 200.0 grams of water.
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Accelerated Chemistry
Chapter 13
Boiling point elevation – when solutes dissolve in liquids, they
points.
the boiling
Same concept as freezing point depression except boiling point
.
kb water = 0.512 oC/m
Why does boiling point elevation occur?
The solute takes up space on the
of a liquid. This decreases the ability of
the liquid to
. Thus, the vapor pressure
. Boiling occurs when the
atmospheric pressure
the vapor pressure. So, an
in energy is
needed to increase the vapor pressure to reach the atmospheric pressure.
= solvent
versus
= solute
“A”
“B”
Which would produce more vapor?
Which would have a higher vapor pressure?
Which would take less energy to raise the vapor pressure to atmospheric pressure?
Which would have a higher boiling point?
Ex1: Calculate the boiling point of a solution of 10.00 grams of NaCl in 200.0 grams of
water.
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Accelerated Chemistry
Chapter 13
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