The document discusses various concepts related to ionic compounds and reactions in aqueous solutions. It defines precipitation reactions as those where insoluble ionic solids called precipitates form from the combination of certain cations and anions. It also explains how to write net ionic equations that show only the actual participants in a reaction. Additionally, it covers topics like acidic and basic solutions, neutralization reactions between acids and bases, and how to recognize acids and bases based on their chemical formulas.

1. Dissolution of
Ionic Compounds
Dr. K. Shahzad Baig
Memorial University of Newfoundland
(MUN)
Canada
Petrucci, et al. 2011. General Chemistry: Principles and Modern Applications. Pearson Canada Inc., Toronto, Ontario.
Tro, N.J. 2010. Principles of Chemistry. : A molecular approach. Pearson Education, Inc

3. Example
What are the aluminum and sulfate ion concentrations in 0.0165 M Al2(SO4)3 ?

4. Precipitation Reactions
Precipitation reactions occur when certain cations and anions combine to produce an
insoluble ionic solid called a precipitate.
In industry, precipitation reactions are used to manufacture numerous chemicals e.g., In
the extraction of magnesium metal from seawater, for instance, the first step is to
precipitate Mg2+ as Mg(OH)2(s).
Net ionic equation
A net ionic equation is an equation that includes only the actual participants in a
reaction, with each participant denoted by the symbol or formula that best represents it.

5. When the two solutions are mixed, neither the Na+ nor the NO−3 ions participate in the
reaction.

6. Problem statement
When aqueous solutions of copper (II) chloride and potassium phosphate are mixed,
a precipitate of copper (II) phosphate is formed. Write a balanced net ionic equation
for this reaction.

8. Predict whether precipitation occurs when the following aqueous solutions are mixed
AgBr(s) is insoluble in water (because rule 3 takes precedence
over rule 4)

9. Acidic and Basic Solutions
experiment shows small numbers of H+ and OH- ions are present even in pure water
Careful measurements show that at 25 oC

10. Neutralization
In a neutralization reaction, an acid and a base react to form water and an aqueous solution
of an ionic compound called a salt.
When the spectator ions are eliminated, the net ionic equation

11. Recognizing Acids and Bases
Acids contain ionizable hydrogen atoms
A substance whose formula indicates a combination of ions with cations is generally a
strong base (for example, NaOH).
weak base is NH3 . Note that ethanol, CH3CH2OH, is not a base. The OH group is not
present as OH-, both in pure ethanol and in its aqueous solutions.

12. Problem statement
When aqueous solutions of copper (II) chloride and potassium phosphate are mixed,
a precipitate of copper (II) phosphate is formed. Write a balanced net ionic equation
for this reaction.

13. Predict whether precipitation occurs when the following aqueous solutions are mixed
AgBr(s) is insoluble in water (because rule 3 takes precedence
over rule 4)

14. Acidic and Basic Solutions
experiment shows small numbers of H+ and OH- ions are present even in pure water
Careful measurements show that at 25 oC

15. Neutralization
In a neutralization reaction, an acid and a base react to form water and an aqueous solution
of an ionic compound called a salt.
When the spectator ions are eliminated, the net ionic equation

16. Recognizing Acids and Bases
Acids contain ionizable hydrogen atoms
A substance whose formula indicates a combination of ions with cations is generally a
strong base (for example, NaOH).
weak base is NH3 . Note that ethanol, CH3CH2OH, is not a base. The OH group is not
present as OH-, both in pure ethanol and in its aqueous solutions.