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Net Ionic Equations
NET IONIC EQUATIONS
I CAN describe a chemical reaction in
solution by writing is total and net ionic
equations.
SOLUBLE vs INSOLUBLE
Not all substances are soluble in water.
 Generally speaking, IONIC COMPOUND
formula units separate into their positive
cations and negative anions in water.
 Covalent compounds simply spread
out…their molecules do not separate.
 Since chemical equations must represent
what is happening in a reaction, we often
write a NET IONIC equation to show what
actually happens in the reaction.

There are three steps involved in
getting to the net ionic equation:
Write the non-ionic equation (aka a
balanced chemical equation)
 Write the total ionic equation
 Write net ionic equation

EXAMPLE

Solutions* of lead (II) nitrate and
potassium iodide are mixed according
to the following equation:
Pb(NO3)2 (aq) + 2 KI (aq)

PbI2 (s) +
2 KNO3 (aq)

*Remember that solution means it is soluble in water!

When you see (aq) following a compound, it means it
is soluble in water. An (s) means it is an insoluble
solid. A (g) represents a gas and is also INSOLUBLE
in water.
Now write the total ionic equation
 Dissociate
or ionize everything
that is:
–Aqueous and Ionic
–Aqueous and Acid
Do NOT Dissociate a solid
Pb(NO3)2 (aq) + 2KI (aq)
 PbI2(s) + 2KNO3 (aq)
Dissociate
Pb2+ (aq) + 2NO3-1(aq) + 2K+1(aq ) + 2I-1(aq) 
PbI2(s) + 2K+1(aq) + 2NO3¯1(aq)
Solids are NOT aqueous so do not dissociate!
SPECTATOR IONS

A SPECTATOR ION is one that does
not change in the reaction…it is not
involved in the reaction and stays the
same on BOTH SIDES of the equation.
Now cancel spectator ions in the
total ionic equation:
Pb2+(aq) + 2NO3-1(aq) + 2K+(aq) + 2I-1(aq)

PbI2(s) + 2K+(aq) + 2NO3-1(aq)
What now remains is the net ionic
equation.
So the net ionic equation is:
Pb2+ (aq) + 2I -1(aq)  PbI2(s)
Example Problem
Chlorine gas is bubbled through a solution of sodium
fluoride. What is the net ionic equation for the
reaction?
1. Write the non-ionic equation:
Cl2(g) + 2 NaF(aq)  F2(g) + 2 NaCl(aq)
Write the total ionic equation:
Dissociate everything that is:
1. Aqueous and ionic or
2. Aqueous and acid
Cl2(g) + 2NaF(aq) 
Cl2(g) +
F2(g) + 2 NaCl(aq)
2Na+1 (aq) + 2F-1(aq)

F2(g) + 2Na+1(aq) + 2Cl-1(aq)
Write the net ionic equation:
Cancel all spectator ions:
Cl2(g) +
2 Na+1 (aq)
+
2 F-1(aq)

F2(g) + 2 Na+1 (aq) + 2 Cl-1(aq)
What remains is the net ionic equation:
Cl2(g) + 2F- 1(aq)

F2(g) + 2Cl-1(aq)
Occasionally there are NO
SPECTATOR IONS.
 In this situation, the TOTAL and the NET
IONIC EQUATIONS are the same.

Practice Problems

Complete the practice problems at the
end of the notesheet.