AP Chemistry
Granada Hills Charter High School ~ 2007
AP Chemistry
Chemical Reactions
Practice for Question #4
Complex Ion Formation
• a concentrated solution of ammonia is
added to a solution of zinc iodide to form a
complex ion.
• 4 NH3 + Zn2+  Zn(NH3)42+
• What precipitate could have been formed
had the reactant been a dilute solution of
ammonia?
• Zinc hydroxide
REDOX
• sodium metal is added to water.
• Na + H2O  Na+ + H2 + OH• Is the resulting solution acidic, basic or
neutral? EXPLAIN and give an example
of how you could prove your response.
• The resulting solution would be basic. This
could be observed through the addition of
phenolphthalein indicator which would turn
pink in base.
Organic
• Chlorine gas is bubbled into to octane
• Cl2 + C10H22  C10H21Cl + H+ + Cl• Describe the relative pH of the resulting
solution as acidic, neutral or basic.
• The solution would be acidic as the
substitution reaction replaces a hydrogen
with chloride releasing H+.
Double Replacement
• dilute acetic acid solution is added to solid
magnesium carbonate.
• 2 HC2H3O2 + MgCO3
2 C2H3O2- + H2O + CO2 + Mg2+
• Would the resulting solution be acidic, basic or
neutral? EXPLAIN. (This would be too difficult to answer especially without Ka values however…)
• The resulting solution would likely be close to or slightly
lower than neutral because acetate is a conjugate base
(from a weak conjugate acid) and the CO2 in water
would be acidic as a non-metal oxide in water produces
an acidic solution.
General Acid/Base, Hydrolysis
• Solid ammonium chloride is added to
water
• NH4Cl + H2O  NH3 (aq) + H3O+ (aq) + Cl(aq)
• Is the resulting solution acidic, basic or
neutral? EXPLAIN
• The ammonium ion is the conjugate acid
of a weak base and it therefore creates an
acidic solution in water.
REDOX
• a solution of tin(II) chloride is added to a
solution of iron(III) sulfate.
• Sn2+ + 2 Fe3+  Sn4+ + 2 Fe2+
• Write and balance the oxidation halfreaction for mass and charge
• Sn2+  Sn4+ + 2 e-
Complex Ion Formation
• an excess of nitric acid solution is added
to a solution of tetraamminecopper(II)
sulfate.
• 4H+ + Cu(NH3)42+  4 NH4+ + Cu2+
• List the spectator ions in this reaction.
• NO3- and SO42- nitrate and sulfate ions
REDOX
• a piece of lithium metal is dropped into a
container of nitrogen gas.
• 6Li + N2  2Li3N
• Besides a redox reaction, how else might
this reaction be classified.
• Synthesis Reaction: a more complex
product made from simple reactants
Lewis Acids and Bases
• the gases boron trifluoride and ammonia
are mixed.
• BF3 + NH3  BF3NH3
• Based on behavior, what type of species is
boron trifluoride in this reaction?
EXPLAIN.
• BF3 is behaving as a Lewis acid as it is
accepting the electron pair provided by
nitrogen in a coordinate covalent bond.
REDOX
• a piece of iron is added to a solution of
iron(III) sulfate.
• Fe + 2 Fe3+  3 Fe2+
• Write the valence electron orbital notation
of the resulting product illustrating and
specifying diamagnetic or paramagnetic.
• [Ar]3d __ __ __ __ __ paramagnetic
Complex Ion Formation
• excess concentrated potassium hydroxide
solution is added to a precipitate of zinc
hydroxide to form a complex ion.
• 2 OH- + Zn(OH)2  Zn(OH)42• What would be observed in this reaction?
• A white solid would dissolve into a clear,
colorless solution.
Precipitation and Qualitative Analysis
• A solution of silver nitrate, iron (III) nitrate,
copper (II) nitrate and zinc nitrate are
treated with 6 M hydrochloric acid
• Ag+ + Cl-  AgCl
• What would be observed in this reaction?
• A white solid would form from a clear and
colorless solution mixture.
Double Replacement
• hydrogen sulfide is bubbled through a
solution of silver nitrate.
• H2S + 2 Ag+  Ag2S + 2H+
• Describe what change would be observed
as the reaction proceeded.
• Gas would be observed bubbling through
a clear and colorless solution forming a
black precipitate.
Lewis Acids and Bases
• solid sodium oxide is added to water.
• Na2O + H2O  2 Na+ + 2 OH• Is the resulting solution acidic, basic or
neutral? EXPLAIN
• Basic. Metal oxides form basic
compounds in water.
Combustion
• 1-Propene ignites in air
• 2 C3H6 + 9 O2  6 CO2 + 6 H2O
• Describe the hybridization and molecular
geometry change about carbon-1 in the
reactant to the carbon in the product.
• sp2 hybridized in a trigonal planar
geometry to sp hybridized in a linear
geometry.
Precipitation and Qualitative Analysis
• Carbon dioxide gas is bubbled through a
solution of barium hydroxide.
• CO2 + Ba2+ + 2OH-  BaCO3 + H2O
• What would be observed in this reaction?
• The initial clear solution would turn milkywhite as the barium carbonate was
formed.
Lewis Acids and Bases
• powdered magnesium oxide is added to a
container of carbon dioxide gas.
• MgO + CO2  MgCO3
• If the product were dissolved in water,
predict the acidity, basicity or neutrality of
the resulting solution.
• The dissociated carbonate ion would
produce a basic solution in water as it is a
conjugate base of a weak acid.
Double Replacement
• dilute nitric acid is added to crystals of
pure calcium oxide.
• H+ + CaO  Ca2+ + H2O
• What would you observe as this reaction
took place?
• The solid, CaO would disappear.
Complex Ion Formation
• excess concentrated sodium hydroxide
solution is added to solid aluminum
hydroxide to form a complex ion.
• Al(OH)3 + 3 OH-  Al(OH)63- [or Al(OH)4-]
• Name the complex formed in this reaction.
• hexahydroxoaluminate
or tetrahydroxoaluminate
Decomposition
• A small amount of manganese dioxide is
added to hydrogen peroxide
• 2H2O2  2H2O + O2
• What would be observed as this reaction
proceeded
• A great amount of heat and water vapor
(steam) is released (exothermic). The
manganese dioxide is not consumed in the
reaction as it serves as the catalyst.
Double Replacement (Metathesis)
• Concentrated hydrochloric acid is added to
aqueous sodium sulfite
• 2 H+ + SO32-  SO2 + H2O
• What bond angle changes take place from
the S-O bond of the reactant to the S-O
bond of the product.
• The sulfite is trigonal pyramidal (approx.
107 while the sulfur dioxide is bent (less
than 120).
Redox
• Solid gold is added to a mixture of
concentrated nitric acid and HCl to form a
complex ion.
• 4 H+ + 4 Cl- + NO3- + Ag 
AgCl4- + NO + 2 H2O
• What is the acid mixture called?
• Aqua regia
Lewis Acids and Bases
• solid calcium oxide is heated in the
presence of sulfur trioxide gas.
• CaO + SO3  CaSO4
• Classify this type of reaction
• This is a Lewis Acid/Base reaction with
CaO behaving as a Lewis Base and SO3
as the Lewis Acid. It is also a synthesis
reaction.
Double Replacement
• a saturated solution of calcium hydroxide
is added to a solution of magnesium
chloride.
• 2 OH- + Mg2+  Mg(OH)2
• List all spectator ions:
• Ca2+ and Cl-
Lewis Acids and Bases
• solid ammonium carbonate is heated.
• (NH4)2CO3  2NH3 + CO2 + H2O
• How would an observer confirm the presence of
the products of this reaction.
EXPLAIN.
• Detection of an ammonia odor and possible
formation of water vapor or droplets could be
detected. It would be difficult to determine the
presence of CO2 without further tests.
Complex Ion Formation
• a concentrated solution of ammonia is
added to a solution of copper(II) chloride
to form a complex ion.
• 4 NH3 + Cu2+  Cu(NH3)42+
• Describe the color change that is observed
• The pale blue solution turns a deep blue
color.
Acid/Base, Precipitation
• sulfuric acid is added to barium hydroxide in
equimolar volumes
• 2 H+ + SO42- + Ba2+ + 2 OH- 
H2O + BaSO4
• What would you observe in conductivity as the
reaction progressed?
• If a conductivity apparatus was utilized, the
indicator bulb would initially burn brightly then
dim to off as the non-conductive solid product
was formed. The dissociation of pure water is
so minimal it likely wouldn’t even be detected by
the apparatus though it is a weak electrolyte.
REDOX
• Chlorine gas reacts with sodium bromide
solution
• Cl2 (g) + 2 Br - (aq)  Br2 + 2 Cl -(aq)
• Which species is the oxidizing agent
• Chlorine is the oxidizing agent
• What would you see as the reaction proceeds?
• The solution would turn brown from the
presence of bromine.
General Acid/Base, Hydrolysis
• Sulfur dioxide gas is bubbled through
water
• SO2(g) + H2O (l)  H2SO3(aq)
• What other major species would be in
solution once equilibrium was established?
• H+ and HSO3(and in small quantity SO32- )
Double Replacement
• equal volumes of dilute equimolar
solutions of sodium carbonate and
hydrochloric acid are mixed.
• CO32- + H+  HCO3• What would occur if the hydrochloric acid
was increased?
• Carbon dioxide and water would be
formed as products.
Precipitation
• A solution of silver nitrate and sodium
chromate are mixed
• 2 Ag+ + CrO42-  Ag2CrO4
• What would be observed as the reaction
proceeded?
• A clear and colorless solution is mixed with
a clear yellow solution and a red
precipitate is formed.
Precipitation
• Solutions of zinc sulfate and potassium
phosphate are mixed.
• 3 Zn2+ + 2 PO43-  Zn3(PO4)2
• When a flame test of the resulting solution
is done what would be observed?
• A lavender or lilac flame color would be
observed
Complex Ion Formation
• a solution of potassium thiocyanate is
added to a solution of iron(III) chloride.
• SCN- + Fe3+  FeSCN2+
• Describe any observation that would occur
in this reaction.
• A colorless and yellow solution would turn
a dark blood red.
REDOX
• an acidified solution of potassium
permanganate is added to a solution of
sodium sulfite.
• 6H++ 2MnO4- +5SO32- 2Mn2++ 3 H2O +5 SO42-
• Write the reduction half-reaction for mass
and charge
• 5 e- + 8 H+ + MnO4-  Mn2+ + 4H2O
• (unlikely candidate for the test as too much time
needed to balancing the redox rxn)
Lewis Acids and Bases
odd reactions
• phosphorus(V) oxytrichloride is added to
water [You shouldn’t have this - too hard with no
choices this year.]
• POCl3 + H2O  H3PO4 + Cl- + H+
• Note that molecular phosphorus
compounds form acids with water.
• PCl5 + H2O  H3PO4 + H2O + Cl- + H+
• PCl3 + H2O  H3PO3 + Cl- + H+
STUDY
Special thanks to Edye Eudell of Westridge Girls’ Academy in Pasadena and Paul Groves, of
South Pasadena High School for Content Contributions, Editing for Assistance in the
development of this PowerPoint