Mix the following solutions in pairs
Write down the solution pairs and record your results
 Potassium Iodide
 Barium Nitrate
 Lead Nitrate

When finished, try Silver Nitrate with Potassium
Iodide.
Precipitate Reactions
Precipitates
 Solubility rules
Using the rules of solubility


Reaction of PbNO3 and KI



Lead II Nitrate and
Potassium Iodide
Both are strong
electrolytes
That means they
completely dissociate
into ions


Adding the
solutions together
will create
something new…
A chemical change
the evidence is the
precipitate.
Look closer at
Lead (II) Nitrate


Strong Electrolyte
Ions completely
dissociate into:
Pb2+ ions
 Nitrate NO3 - Ions
 Lead
Pb (NO)3
The KI does the same thing
Posassium K+
ions
and Iodide I- ions
form.

They are floating
around in the
water.
(an aqueous solution)
When the lead and
the iodide ions come
into contact, they
form a precipitate

The precipitate falls
to the bottom,
spectator ions are
left in solution
The rules can be broken into 4
categories.
1
soluble
no exceptions
2
soluble
some exceptions
3
not soluble
some exceptions
4
not soluble
few exceptions
Solubility Rules: Always Always Soluble
1. Always Soluble:

Li+, Na+,K+, NH4+
 Group
1A(Alkali Metals) and ammonium
compounds are soluble.

C2H3O2-, NO3-,ClO3-, ClO4 Acetates,
Nitrates, Chlorates, Perchlorates
are all soluble.
The solubility rules: Usually soluble
 Cl-,
Br-, I-
Most chlorides, bromides and
Iodides are soluble
•
F-
Most fluorides are soluble
•
SO42-
Most Sulfates are soluble
Exceptions AP/H
(Ag) Silver: AgCl, AgBr, AgI
(Pb) Lead (II) PbCl2, PbBr2, PbI2
(Hg) Mercury (I): Hg2Cl2, Hg2Br2, Hg2I2
Exceptions CBS-PM
Calcium, Barium, Strontium, Lead,
Magnesium
MgF2, CaF2, SrF2, BaF2 Lead (II) PbF2
Exceptions CBS/PBS
Calcium, Strontium, Barium, Lead (II)
CaSO4
PbSO4
SrSO4 BaSO4
The solubility rules: Usually NOT
Soluble
O2-, OHMost hydroxides and
oxides are
insoluble
Exceptions: CBS
CaO, Ca(OH)2
SrO, Sr(OH)2
BaO, Ba (OH)2
And the ‘always group’ of
Alkali metals and Ammonium
The solubility rules: Insoluble Ions


Not soluble
CO32- PO43-
SO32- S2- C2O42- CrO42-
Exceptions: The things that are
always soluble.
Group 1A (Alkali Metals)
Li2CO3, Na2CO3… etc
Ammonium compounds
(NH4)2CO3
Types of reactions

Remember net ionic equations?
Showing everything in the reaction
vessel (beaker, well plate, test tube…
Sometimes parts of the equation do
nothing but sit and watch.
Spectators
Complete ionic vs. net ionic
Sodium sulfate + Barium Chloride react to form Solid barium
sulfate and Sodium chloride
2 Na+ (aq) + SO42- (aq) + Ba2+ (aq) + 2 Cl- (aq) 
BaSO4 (s) + 2 Na+ (aq) + 2 Cl- (aq)
NaCl is a strong electrolyte, so it does not combine to form a
solid
Stoichiometry in Aqueous Reactions
What volume of 0.200 M copper (II) sulfate is required to
react with 50.0mL if 0.100 M NaOH?
1)
Write the net ionic equation
Cu 2+ (aq) + 2 OH- (aq)  Cu(OH)2 (s)
What volume of 0.200 M copper (II) sulfate is required to react
with 50.0mL if 0.100 M NaOH?
find the moles of each reactant needed:
nOH- =
nCu2+ =