Mix the following solutions in pairsWrite 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.
Pb (NO)3Look closer at Lead (II) Nitrate
Strong Electrolyte
Ions completely dissociate into:
Lead Pb2+ ions Nitrate NO3
-
Ions
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
Exceptions AP/H
(Ag) Silver: AgCl, AgBr, AgI
(Pb) Lead (II) PbCl2, PbBr2, PbI2
(Hg) Mercury (I): Hg2Cl2, Hg2Br2, Hg2I2• F-
Most fluorides are
soluble
Exceptions CBS-PM
Calcium, Barium, Strontium, Lead, Magnesium
MgF2, CaF2, SrF2, BaF2 Lead (II) PbF2
• SO42-
Most Sulfates are
soluble
Exceptions CBS/PBS
Calcium, Strontium, Barium, Lead (II)
CaSO4 SrSO4 BaSO4
PbSO4
The solubility rules: Usually NOT SolubleO2-, OH-
Most 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 CO3
2- PO43- SO3
2- S2- C2O42- CrO4
2-
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+ =
