REACTIONS IN AQUEOUS
SOLUTIONS: METATHESIS
REACTIONS AND NET IONIC
EQUATIONS
Experiment 21
Page 227
Dr. Scott Buzby, Ph.D.
OBJECTIVES
To become familiar with writing equations for
metathesis reactions
 Understand the difference between molecular,
ionic and net ionic equations
 Determine the solubility of a salt by using
solubility rules
 Study the effect of temperature on solubilty
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DEFINITIONS
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Solubility
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Saturation
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The point at which no more solute can dissolve in a solution
and additional amounts of it will appear as a precipitate.
Precipitate
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The property of a substance to dissolve in another substance
to form a homogenous solution
Solute – The substance being dissolved
Solvent – The substance doing the dissolving
Aqueous solution – A solution where water is the solvent
Homogenous solution – A stable mixture that is uniform in
composition where the solute will not settle out, no matter
how long the solution sits, and it cannot be removed by
physical means (ex. filtering)
the formation of a solid in a solution
Electrolyte
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any substance containing free ions that make the substance
electrically conductive (ionic solution)
METATHESIS REACTION
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An aqueous chemical reaction in which the
cations (+ Ions) and anions (- ions) appear to
change partners
AX  BY  AY  BX
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In order for a net change in the solution to occur
(i.e. a reaction), ions must be removed from the
solution by the formation of
a precipitate
 a weak electrolyte or nonelectrolyte
 a gas that escapes from solution
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METATHESIS REACTION CON’T.
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Formation of a Precipitate
NaCl( aq)  AgNO3( aq)  NaNO3( aq)  AgCl( s )
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Formation of a Gas
2 HCl( aq)  Na2 S ( aq)  2 NaCl( aq)  H 2 S ( g )
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Formation of a Weak Electrolyte
HCl( aq)  NaOH ( aq)  NaCl( aq)  H 2O(l )
IONIC AND NET IONIC EQUATIONS

Molecular Equation
NaCl( aq)  AgNO3( aq)  NaNO3( aq)  AgCl( s )
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Ionic Equation
Na(aq)  Cl(aq)  Ag(aq)  NO3( aq)  Na(aq)  NO3( aq)  AgCl( s )
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Net Ionic Equation
Ag   Cl   AgCl(s )
PROCEDURE
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Part A: Metathesis Reactions
Mix the solutions in small test tubes and record your
observations (precipitate, gas bubbles, heat, nothing)
on the report sheet
 Write out the three reactions according to your
observations
 Skip reactions 6 - 9 & 14 - 15
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PROCEDURE CON’T.
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Part B: Solubility, Temperature and
Crystallization
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Prepare the solution as per instructions on Pg. 231
Cool the solution to ~10°C by dipping beaker into ice
water (DO NOT add ice to solution) and stirring
carefully
Observe shape of crystals and filter COLD solution
into an evaporating dish
Evaporate filtrate to half of its volume using a
Bunsen burner and a ring stand (additional crystals
should form)
Filter HOT solution into 100mL beaker and compare
shape of crystals with first batch
Cool the filtrate to ~10°C with ice while stirring to
HOMEWORK – DUE NEXT WEEK
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Part A
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Report Sheet – Pages 233 – 236
Part B
Solubility Graph – Page 235
 Questions – Pages 235 – 236
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Questions
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Page 236
Pre-lab
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Experiment #22 – Page 243