5 Steps to a Net Ionic Equation
Step 1. Write the balanced molecular equation.
Predict the products, just as you have done with reactions thus far. The reactions
that you will need to pay particular attention to are all double replacement reactions
and most single replacement reactions.
Eg: 2AgNO
3
+ PbCl
2
2AgCl + Pb(NO
3
)
2
Step 2. Look at each substance and determine if it will ionize in water.
Each substance will ionize if:
You have to make this decision for each reactant and each product in the
balanced molecular equation from step 1. Use the following rules to help.
Rule 1. it is a strong acid. (there are 6 of these HCl, HBr, HI, H
2
SO
4
, HNO
3
, and HClO
4
)
Rule 2. it is a strong base. (there are 6 main players here: LiOH, NaOH, KOH,
Ca(OH)
2
, Sr(OH)
2
, and Ba(OH)
2
most of the rest of the metal hydroxides are
insoluble and don’t ionize.)
Rule 3. it is a soluble ionic compound. (anything soluble according to the
solubility rules handout)
Step 3. Write the complete or total ionic equation.
List all your reactants and products in their aqueous form, which is as aqueous ions, as
just aqueous, as solids, as liquids, or as gases as appropriate. This is what you were
determining in step 2. (For example NaOH should be written as Na
+1
+ OH
-1
, H
2
SO
4
should be written as 2H
+1
+ SO
4
-2
, Mg would be just Mg(s), H
2
would be H
2
(g), AgCl
would be AgCl(s) note: any coefficient on an ionic compound will be distributed
through both ionic pieces.
Step 4. Cancel out any spectator ions.
Look for anything in the total ionic equation that hasn’t changed. These substances
will be exactly the same on both sides of the equation. These substances are not really
involved in the chemical change that the reaction equation describes. They are NOT
included in the net ionic equation.
Step 5. Write the net ionic equation.
Anything not cancelled out in step 4 is included in the net ionic equation.
Make sure the equation is balanced with the simplest ratio of whole numbers.