AP Net Ionic Equations
AP equations are found in the free response
section of the AP test. You will have 3
equations following by a question about
the reaction. The equations are of mixed
types.
The sections is worth 15 points and is 10%
of the free response grade. Free
response is 50% of the total AP test grade.
All AP equations “work.” In each case, a
reaction will occur. These equations need
to be written in net ionic form. All
spectator ions must be left out and all ions
must be written in ionic form.
• Answer 3 equations that must be
balanced.
• Each equation is followed by a question.
• 1 pt for reactants, 2 points for products,
and 1 pt for each question.
• Strong Acids are:
Exception: concentrated sulfuric acid-keep
together because it really is 97% H2SO4
and 3% water in the jug.
• Strong Bases are:
Weak acids and bases keep together
• All molecular substances and nonsoluble
compounds must be written together (not
ionized!).
Know your solubility rules!!!
– Ca(OH)2 and Sr(OH) 2 are moderately soluble and
can be written together or as ions.
– Ba(OH)2 is soluble and Mg(OH)2 is insoluble.
– CaSO4 and SrSO4 are moderately soluble and can be
written together or as ions.
– Weak electrolytes, such as acetic acid, are not
ionized.
– Solids and pure liquids are written together, also.
– A saturated solution is written in ionic form while a
suspension is written together.
Double Replacement
Two compounds react to form two new
compounds. No changes in oxidation
numbers occur. All double replacement
reactions must have a “driving force” that
removes a pair of ions from solution.
• Manganese(II) nitrate solution is mixed
with a sodium hydroxide solution
• Excess hydrochloric acid is added to an
aqueous solution of potassium sulfite
• Hydrogen sulfide gas is bubbled through a
solution of lead(II) nitrate
• A solution of ammonium sulfate is added
to a potassium hydroxide solution
• Solutions of tripotassium phosphate and
zinc nitrate are mixed
• Gaseous hydrofluoric acid reacts with solid
silicon dioxide.
Single Replacement Rxns
Treat like redox reactions.
Reaction where one element displaces
another in a compound. One element is
oxidized and another is reduced.
A + BC  B + AC
+ charges replace + and
– charges replace -
• Active metals replace less active
metals or hydrogen from their
compounds in aqueous solution.
• Active nonmetals replace less active
nonmetals from their compounds in
aqueous solution. Each halogen will
displace less electronegative (heavier)
halogens from their binary salts.
Examples
• A piece of aluminum metal is added to a
solution of silver nitrate
• Small chunks of solid sodium are added to
water
• Chlorine gas is bubbled into a solution of
sodium bromide
• Magnesium turnings are added to a
solution of iron(III) chloride
Anhydrides
Anhydride means “without water.”
Water is a reactant in each of these
equations.
Memorize the Rules
Look for:
1. Oxides + H2O
a. metallic oxide + H2O  base
b. nonmetallic oxide + H2O  acid
2. Metal hydride + H2O metal hydroxide + H2
3. Group 1 and 2 nitride + H2O
metal hydroxide + NH3
4. Phosphorus halide + H2O 
H3PO4 or H3PO3 + H(halide) acid
Examples
• Excess water is added to solid calcium
hydride
• Solid lithium hydride is added to water
• Solid dinitrogen pentoxide is added to
water
• Solid potassium oxide is added to water
• Phosphorus pentachloride solid is added
to water
• Methylamine gas is bubbled into distilled
water
Oxidation-Reduction Reactions
• Redox reactions involve the transfer of
electrons. The oxidation numbers of at
least two elements must change.
• Single replacement, some combination
and some decomposition reactions are
redox reactions.
• To predict the products of a redox
reaction, look at the reagents given to
see if there is both an oxidizing agent
and a reducing agent.
• When a problem mentions an acidic or
basic solution, it is probably redox.
Common oxidizing agent
Product formed
MnO4- in acidic solution
Mn2+
MnO2 in acidic solution
Mn2+
MnO4- in neutral or basic
solution
MnO2 (s)
Cr2O72- in acidic solution
Cr3+
HNO3, concentrated
NO2
HNO3, dilute
NO
H2SO4, hot, concentrated
SO2
Common oxidizing agent
Product formed
Metal-ic ions
Metal-ous ions
Free halogens
Halide ions
Na2O2
NaOH
HClO4
Cl-
H2O2
H2O
Common reducing agent
Product formed
Halide ions
Free metals
Sulfite ions or SO2
Free halogen
Metal ions
Sulfate ions
Nitrite ions
Nitrate ions
Common reducing agent
Product formed
Free halogens, dilute basic solution Hypohalite ions
Free halogens, conc. basic solution Halate ions
Metal-ous ions
Metal-ic ions
H2O2
O2
C2O42-
CO2
Examples
• A solution of tin(II) chloride is added to an
acidified solution of potassium
permanganate.
• Hydrogen peroxide solution is added to a
solution of iron(II) sulfate
• Potassium permanganate solution is
added to a solution of oxalic acid acidified
with a few drops of sulfuric acid.
• A piece of iron is added to a solution of
iron(III) sulfate.
• Solid sodium dichromate is added to an
acidified solution of sodium iodide
• Potassium permanganate is mixed with an
alkaline solution of sodium sulfite
• Copper (II) sulfide is oxidized by dilute
nitric acid.
• A solution of potassium iodide is added to
an acidified solution of potassium
dichromate.
Acid-Base Neutralization Rxns
Acids react with bases to produce water
and salts.
Examples
Hydrogen sulfide gas is bubbled through a
solution of potassium hydroxide
• A solution of sodium hydroxide is added to
a solution of sodium dihydrogen
phosphate until the same number of moles
of each compound has been added
• Nitric acid is added to crystals of pure
calcium oxide
• Carbon dioxide is bubbled through a
solution of sodium hydroxide
Decomposition Reactions
• Reaction where a compound breaks down
into two or more elements or compounds.
Heat, electrolysis, or a catalyst is usually
necessary.
Memorize the rules!
1. Metal Carbonate  Metal oxide + CO2
2. Metal Chlorate  Metal chloride + O2
3. Hydrogen peroxide water + oxygen
4. Ammonium carbonate ammonia +
water + carbon dioxide
5. Sulfurous acid  Sulfur dioxide + water
6. Carbonic acid  carbon dioxide + water
Examples
• A solution of hydrogen peroxide is
heated
• Magnesium carbonate is heated
• Potassium chlorate is heated in the
presence of manganese dioxide
• Solid ammonium carbonate is heated
Addition Reactions
• Two or more elements or compounds
combine to form a single product.
Memorize the rules! Most of these
should already look familiar.
1. 2 cmpds  form one compound
2. If excess use the higher oxidation number
If limited use the lower oxidation number
3. Nonmetal oxide + water  acid
4. Metal oxide + water  base
5. Metal oxide + sulfur dioxide Metal sulfite
6. Metal oxide + carbon dioxide  metal
carbonate
Examples
• Magnesium oxide is added to a
container of carbon dioxide gas
• Solid calcium oxide is heated in the
presence of sulfur trioxide gas
• Calcium metal is heated strongly in
nitrogen gas
• The gases boron trifluoride and
ammonia are mixed
Combustion Reactions
-Elements or compounds combine with
oxygen.
Memorize these rules.
1. Hydrocarbon + oxygen  carbon
dioxide + water
2. ammonia + oxygen  NO + H2O
if excess O2  NO2 + H2O
3. Nonmetal hydride + oxygen  nonmetal
oxide+ water
4. Nonmetal sulfide+oxygen  nonmetal
oxide + sulfur dioxide
• Methane is burned in the presence of
oxygen
• Lithium metal is burned in air
• Solid zinc sulfide is heated in an excess of
oxygen
• A piece of solid bismuth is heated strongly
in oxygen
Complex Ion Reactions
• Complex ions are made up of a
____________ and a _____________.
[Co(NH3)6]+3 is the complex ion
NH3 is the ligand, Co is the metal
• Possible metals: Cu/Zn/Ag/Cd/Fe/Al
• Possible ligands: NH3, OH-1, SCN-1
• Magic number? Double charge to get
magic number
•
•
Exceptions to the trick:
**[Al(OH)4]- **[Fe(SCN)]2+
Example:
[Co(NH3)6] Cl3
NH3 is the ligand, [Co(NH3)6]+3 is the
complex ion
Common complex ions on AP equations
**[Al(OH)4]- tetrahydroxoaluminate ion
formed from: (Al or Al(OH)3 or Al3+ + OH-)
[Ag(NH3)2]+ diamminesilver(I) ion
formed from (Ag+ + NH3)
[Zn(OH)4]2- tetrahydroxyzincate ion
formed from (Zn(OH)2 + OH-)
[Zn(NH3)4]2+ tetramminezinc ion
formed from (Zn2+ + NH3)
[Cu(NH3)4]2+ tetraminecopper(II) ion
formed from (Cu2+ + NH3)
[Cd(NH3)4]2+ tetraminecadmium(II) ion
formed from (Cd2+ + NH3)
**[Fe(SCN)]2+ thiocyanairon(III) ion
formed from (Fe3+ + SCN-)
[Ag(CN)2]- dicyanoargentate(I) ion
formed from (Ag+ and CN-)
Remember the following when writing
complex ion reactions:
1. Acid to complex ion  break it up
2. Acid to NH3 complex  NH4+ + breakup
complex ion
3. HCl + Ag complex  AgCl + Breakup
complex ion
Examples
•
Concentrated (15M) ammonia is added
in excess to a solution of copper (II)
nitrate
• Dilute hydrochloric acid is added to a
solution of tetraminecopper (II) sulfate
• A suspension of zinc hydroxide is treated
with concentrated sodium hydroxide
solution
• Solid silver chloride is added to a
concentrated solution of ammonia
• Hydrochloric acid is added to a solution of
dihydroxysilver bromide