CHAPTER 14
Ionic Compounds and Solution
Formation
Ionic Compounds in Solution
• Soluble in polar (dipole) solvent only!
• Solid ionics have equal totals
of positive and negative charges
• Solid ionics have a crystal lattice structure
• In solution, ions separate and are free to
move around
– This is why solutions of ionic substances can
conduct electricity
• (Video in AP Chemistry, Power Points folder, “Salt
Water Conductivity”
Dissolving Ionic Compounds
• Charged ends of water (a dipole) attract ions
and cause dissolving
• http://www.mpcfaculty.net/mark_bishop/NaCl_di
ssolves.htm
• Hydration
– Dissolving with H2O as the solvent
• Hydrate
– Compound with trapped H2O in its crystal lattice
– Copper (II) Sulfate Pentahydrate
Heat of Solution
• Based on bond changes (last chapter!!)
– Solute-solute bonds break
• Endothermic
– Solvent-solvent bonds break
• Endothermic
– Solvent-solute bonds form
• Exothermic
• Endothermic overall =
• Exothermic overall =
Dissociation Equations and
Concentrations
• Examples
Solubility Equilibria
• Ionic compounds have different solubilities
• Compounds that are very slightly soluble form an
equilibrium between solid compound and the
ions
– Example
AgOH (s)
Ag+ (aq) + OH- (aq)
-There would not be very many of the ions, but there would be
some
-Example: ppt will dissolve until no more can dissolve
– Precipitation Reactions
Solid (precipitate) formed when 2 ionic solutions are mixed
Solubility Rules
• Be able to use the solubility rules again!!
Will be given on the test!!
Solubility Rules
1. Group 1 and Ammonium compounds ARE soluble
2. Acetate, Nitrate, and chlorate compounds ARE soluble
3. Group 17 (other than F) ARE soluble EXCEPT when with Ag,
Hg2+2, and Pb
4. Sulfates ARE soluble EXCEPT when with Ba, Sr, Pb, Ca, Ag,
Hg2+2
5. Carbonates, Hydroxides, Oxides, Sulfides, Phosphates,
Oxalates are INSOLUBLE
• Predict, write, balance double displacement reactions
– Example
• Potassium chloride + Silver (I) nitrate 
Net Ionic Equations
• Shows only the compounds and ions that
undergo a change
• Spectator Ions
– There before and after – unchanged during a reaction
– “watch” reaction
• Writing Net Ionic Equations
– Write all aqueous (soluble) compounds as ions.
Leave insoluble compounds as the full compound.
– Cancel out spectator ions
– Write “new” equation = NET IONIC EQN
Net Ionic Equations
• Examples
– Potassium chloride + Silver (I) nitrate 
Potassium sulfate + Barium nitrate
Short cut:
Potassium chloride + Lead (II) nitrate 
Another question…What if they’re all aq??
Molecular Electrolytes
• Some molecular compounds can conduct
electricity when dissolved.
– Example
• HCl  H+ (aq) + Cl- (aq)
• Ionization
– Formation of ions because of action of solvent –
happens usually with acids and bases
• Hydronium
– Seen when an acid is placed in water
– H2O + H+ -> H3O+
Electrolytes
• Strong electrolyte
– Ionizes almost completely
• Weak electrolyte
– Gives low concentration of ions in aqueous
solution
– DOES NOT INDICATE DANGER VALUE!!
• It is a measure of ability to ionize only!!
Properties of Electrolytes
• Conductivity
– Strong electrolytes are more conductive
(breaks apart into more ions!)
• Water
– Water does have ions!
– Tap water vs. dH2O
• Colligative Properties
– BP elevation and FP depression  depend
on solute concentration!!
Colligative Properties
• Electrolytes affect colligative properties
more than nonelectrolytes!!
• Need to calculate molality based on
numbers of particles formed!!
• Example: What is the expected change in
FP of water if 62.5g Ba(NO3)2 is dissolved
in 1.00kg of water?
More practice
• What is the anticipated change in freezing
point if 2.0mol NaCl is dissolved in 1.0kg
water?