Ionic Equations....
What’s really swimming around.
And what’s not swimming around.
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Electrolytes: cmpds whose aqueous solutions conduct
electricity. (refer to solubility rules). Electrolytic
solutions must contain ions.
Nonelectrolytes: cmpds whose solutions don’t conduct
electricity. No ions are present in solution.
For a RXN to occur, at least one product must a non-electrolyte.
An insoluble solid (s) or a molecular substance such as a gas (g),
or liquid (l) [as in H2O(l)]
If everything remains aqueous (aq), no reaction occurs.
All particles are ions and are spectators.
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Double Replacement Reactions
Or to impress your friends.
Also called:
Metathesis reactions
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KI(aq) + Pb(NO3)2(aq)  KNO3(aq) + PbI2(s)
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Equation:
2KI(aq) + Pb(NO3)2(aq)  2KNO3(aq) + PbI2(s)
Overall Ionic Equation:
2K+ + 2IBeaker A
+
Pb2+
+ 2NO3-
Beaker B
2K+ + 2NO3- + PbI2(s)
Beaker C
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Equation:
2KI(aq) + Pb(NO3)2(aq)  2KNO3(aq) + PbI2(s)
Overall Ionic Equation:
2K+ + 2I-
+
Pb2+
+ 2NO3-
2K+ + 2NO3- + PbI2(s)
Net Ionic Equation: (Cross out the spectator ions)
Pb2+ + 2I
PbI2(s)
These are the ions that form the product
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All group 1 cmpds are soluble!
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Let’s Take a Quiz!!
Which one of the following substances is insoluble in
water?
a)
b)
c)
d)
e)
RbOH
KSCN
BaCO3
LiBr
Na3PO4
What do these cmpds look like when they dissolve?
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What do these cmpds look like when they dissolve?
Which one of the following substances is insoluble in
water?
H2O
a) RbOH
b) KSCN
c) BaCO3
d) LiBr
e) Na3PO4
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Which one of the following is an insoluble base?
a)
b)
c)
d)
e)
RbOH
Ba(OH)2
Al(OH)3
LiOH
KOH
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Which one of the following salts is insoluble in water?
a)
b)
c)
d)
e)
FeCl3
Al2(SO4)3
Cr(NO3)3
(NH4)2CO3
AgCl
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Which one of the following salts is insoluble in water?
a)
b)
c)
d)
e)
MgSO4
KNO3
AgBr
FeCl3
NaBr
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What is the total ionic equation for the following formula unit
equation?
BaCl2(aq) + Na2SO4(aq) --> BaSO4(s) + 2NaCl(aq)
[Ba2+(aq)+2Cl-(aq)] + [2Na+(aq)+SO42-(aq)] 
BaSO4(s) + 2Na+(aq)+2Cl-(aq)
Let’s find the net ionic equation:
(Cross out all the Spectator ions.)
Net ionic equation:
Ba2+ + SO42-  BaSO4(s)
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Common Strong Acids and Bases:
Strong acids are completely separated into their ions in water.
Strong bases are strong electrolyes also. (high solubility)
Strong Acids:
Chloric,
Hydrobromic,
Hydrochloric,
Hydroiodic,
Nitric,
Sulfuric,
Perchloric
Strong Bases:
HClO3
HBr
HCl
HI
HNO3
H2SO4
HClO4
Group 1A metal hydroxides
(LiOH, NaOH, KOH,
RbOH, CsOH)
Heavy Group 2A metal hydroxides
[Ca(OH)2, Sr(OH)2, and
Ba(OH)2]
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What is a strong Acid?
An Acid that is 100% ionized in water.
Strong Acids:
100% ionized (completely dissociated) in water.
HCl + H2O

H3O+ + Cl-
often written as:
HCl

H+ + Cl16
What is a strong Base?
A base that is completely dissociated in water (highly soluble).
NaOH(s)  Na+ + OHStrong Bases:
Group 1A metal hydroxides
(LiOH, NaOH, KOH,
RbOH, CsOH)
Heavy Group 2A metal hydroxides
[Ca(OH)2, Sr(OH)2, and
Ba(OH)2]
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RXN: Strong acid and a strong base.
HCl(aq) + NaOH(aq)  HOH(l) + NaCl(aq)
strong
H+
+
nonelectrolyte electrolyte
strong
Cl-
+
Na+
+
OH-
H2O(l) + Na+ + Cl-
“this is the total or overall ionic equation”
H+ + OH-  H2O(l)
Cross out the spectators to find the
NET IONIC EQUATION
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Strong and Weak acids
Strong Acids:
HClO4 H2SO4
HNO3
HI
HBr
HCl
HClO3
Weak Acids:
“The Rest”
Weak electrolytes
Strong electrolytes
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Strong Acids:
100% ionized (completely dissociated) in water.
HCl + H2O  H3O+ + ClNote the “one way arrow”.
Weak Acids:
Only a small % (dissociated) in water.
HC2H3O2 + H2O  H3O+ + C2H3O2Note the “2-way” arrow.
Why are they different?
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Strong Acids:
HCl HCl
HCl
HCl
HCl
(H2O)
ADD WATER to MOLECULAR ACID
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Strong Acids:
Cl-
(H2O)
H 3O +
H 3O +
H 3O +
Cl-
H3O+ ClH 3O +
ClCl-
Note: No HCl molecules remain in
solution, all have been ionized in water.
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Weak Acid Ionization:
HC2H3O2
HC2H3O2
HC2H3O2
HC2H3O2
HC2H3O2
(H2O)

Add water to MOLECULES of WEAK Acid
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Weak Acid Ionization:
HC2H3O2
HC2H3O2
HC2H3O2
HC2H3O2
HC2H3O2
(H2O)

H30+
C2H3O2-
Note: At any given time only a small portion of the acid
molecules are ionized and since reactions are running in
BOTH directions the mixture composition stays the same.
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What is the total ionic equation for the following formula
unit equation?
HF(aq) + KOH(aq)  KF(aq)
+
H2O(l)
weak
strong
strong electrolyte non-electrolyte
Overall ionic equation:
HF(aq) + K+(aq)+OH-(aq)  K+(aq)+F-(aq) + H2O(l)
Net ionic equation: (Cross out the spectators)
HF(aq) + OH-(aq)  F-(aq) + H2O(l)
HF is a weak acid
weak electrolyte
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What is the total ionic equation for the following formula unit
equation?
HC2H3O2(aq) + NaOH(aq)
weak acid
strong base

NaC2H3O2(aq) + H2O(l)
strong electrolyte weak electrolyte
Overall ionic equation:
HC2H3O2(aq) + Na+(aq)+OH-(aq)  Na+(aq)+ C2H3O2 -(aq) + H2O(l)
Net ionic equation: (Cross out the spectators)
HC2H3O2(aq) + OH-(aq)  C2H3O2 -(aq) + H2O(l)
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Net Ionic equations with Single
Replacement RXNs:
Cu(s) + 2AgNO3(aq)  Cu(NO3)2(aq) + 2Ag(s)
Over-all:
Cu(s) + 2Ag+ + 2NO3-  Cu2+ + 2NO3- + 2Ag(s)
Cross out the spectator ions.
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Net Ionic equations with Single Replacement RXNs:
Cu(s) + 2AgNO3(aq)  Cu(NO3)2(aq) + 2Ag(s)
Over-all: Cu(s) + 2Ag+ + 2NO3-  Cu2+ + 2NO3- + 2Ag(s)
Net ionic Eq.: Cu(s) + 2Ag+
 Cu2+ + 2Ag(s)
Copper is more reactive
than silver!
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Let’s try: Mg in HCl(aq)
Mg(s) + 2HCl(aq)  MgCl2(aq) + H2(g)
Mg + 2H+ + 2Cl-  Mg2+ + 2Cl- + H2(g)
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Fe in AgNO3(aq)
HCl and NaHCO3(aq) 
NaOH and H3PO4(aq)
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Study for a Quiz!
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