AP Chemistry Net Ionic Equations Review Answers
Olympus High School – Spring 2011
NOTE: The following equations are NOT balanced! They show the products formed, but not necessarily the
correct ratios. Where multiple answers are given, the first answer listed is the most commonly produced or most
easily predicted product. Other listed products are possible, but not as common or easy to predict (and not
necessarily expected as answers on the exam).
Review #7 (1989 AP Exam)
a) solutions of zinc sulfate and sodium phosphate are mixed.
Zn2+(aq) + PO43-(aq) => Zn3(PO4)2(s) {or ZnHPO4}
b) solutions of silver nitrate and lithium bromide are mixed.
Ag+(aq) + Br-(aq) => AgBr(s)
c) a stream of chlorine gas is passed through a solution of cold, dilute sodium hydroxide.
Cl2(g) + OH-(aq) => OCl-(aq) + Cl-(aq) + H2O (l)
d) excess hydrochloric acid solution is added to a solution of potassium sulfite.
H+(aq) + SO32-(aq) => H2O (l) + SO2 (g) [or H2SO3]
e) a solution of tin(II) chloride is added to an acidified solution of potassium permanganate.
Sn2+(aq) + H+(aq) + MnO4-(aq) => Sn4+(aq) + Mn2+(aq) + H2O (l)
f) a solution of ammonium thiocyanate is added to a solution of iron(III) chloride.
Fe3+(aq) + SCN-(aq) => Fe(SCN)2+(aq) [or Fe(SCN)63-(aq)]
g) samples of boron trichloride gas and ammonia gas are mixed.
BCl3 (g) + NH3 (g) => Cl3B:NH3 (g) {Lewis Acid-Base}
h) carbon disulfide vapor is burned in excess oxygen.
CS2(g) + O2(g) => CO2(g) + SO2(g) [or SO3(g)]
Review #8 (1997 AP Exam)
a) excess potassium hydroxide solution is added to a solution of aluminum nitrate.
OH- (aq) + Al3+ (aq) => Al(OH)3 (s) (or Al(OH)4-; Al(OH)4(H2O)2-; Al2O3; Al2O3òx H2O; AlO2-)
b) a solution of sodium bromide is added to an acidified solution of potassium bromate.
Br- (aq) + H+ (aq) + BrO3- (aq) => Br2 (l) + H2O (l)
c) sulfur dioxide gas is bubbled into distilled water.
SO2 (g) + H2O (l) => H2SO3 (aq) (or => H+ + HSO3-; or => H+ + HSO3- + SO32-)
d) phosphine (phosphorus trihydride) gas is bubbled into liquid boron trichloride.
PH3 (g) + BCl3 (l) => PH3BCl3 (l)
e) hydrogen gas is passed over hot iron(II) oxide powder.
H2 (g) + FeO (s) => Fe (s) + H2O (l)
f) solid potassium amide is added to distilled water.
KNH2 (s) + H2O (l) => NH3 (aq) + OH- (aq) + K+ (aq) (or => NH4OH + OH- + K+)
g) a strip of magnesium metal is heated strongly in pure nitrogen gas.
Mg (s) + N2 (g) => Mg3N2 (s)
h) a solution of nickel chloride is added to a solution of sodium sulfide.
Ni2+ (aq) + S2- (aq) => NiS (s) (or Ni2+ + H2S => NiS + H+; or Ni2+ + HS- => NiS + H+)
Review #9 (1985 AP Exam)
a) sodium metal is added to water.
Na(s) + H2O (l) => Na+(aq) + OH-(aq) + H2(g)
b) dilute sulfuric acid is added to a solution of lithium hydrogen carbonate.
H+(aq) + HCO3-(aq) => H2O (l) + CO2(g)
c) ethanol and formic acid (methanoic acid) are mixed and warmed.
C2H5OH (l) + HCOOH (l) => HCOOC2H5 (l) + H2O (l)
d) excess concentrated potassium hydroxide solution is added to a precipitate of zinc hydroxide.
OH-(aq) + Zn(OH)2(s) => H2O (l) + ZnO22-(aq) [or Zn(OH)42-(aq)]
e) the gases boron trifluoride and ammonia are mixed.
BF3(g) + NH3(g) => F3B:NH3 (g) {Lewis acid-base reaction}
f) a solution of tin(II) chloride is added to a solution of iron(III) sulfate.
Sn2+(aq) + Fe3+(aq) => Sn4+(aq) + Fe2+(aq)
g) phosphorus(V) oxytrichloride is added to water.
POCl3 (g) + H2O (l) => H3PO4(aq) + H+(aq) + Cl-(aq)
h) an acidified solution of potassium permanganate is added to a solution of sodium sulfite.
H+(aq) + MnO4-(aq) + SO3-(aq) => Mn2+(aq) + SO42-(aq) + H2O (l)
Review #10 (1992 AP Exam)
a) an excess of sodium hydroxide solution is added to a solution of magnesium nitrate.
OH- (aq) + Mg2+ (aq) => Mg(OH)2 (s)
b) solid lithium hydride is added to water.
LiH (s) + H2O (l) => Li+ (aq) + OH- (aq) + H2(g)
c) solutions of ammonia and hydrofluoric acid are mixed.
NH3 (aq) + HF (aq) => NH4+ (aq) + F- (aq)
d) a piece of aluminum metal is added to a solution of silver nitrate.
Al (s) + Ag+ (aq) => Al3+ (aq)+ Ag (s)
e) a solution of potassium iodide is electrolyzed.
I- (aq) + H2O (l) => I2 (s) (or I3- (aq)) + H2 (g) + OH- (aq)
f) solid potassium oxide is added to water.
K2O (s) + H2O (l) => K+ (aq) + OH- (aq)
g) an excess of nitric acid solution is added to a solution of tetraamminecopper(II) sulfate.
H+ (aq) + Cu(NH3)42+ (aq) => Cu2+ (aq) + NH4+ (aq)
h) carbon dioxide gas is bubbled through water contain a suspension of calcium carbonate.
CO2 (g) + H2O (l) (or H2CO3(aq)) + CaCO3 (s) => Ca2+ (aq) + HCO3- (aq)
Review #11 (1993 AP Exam)
a) A strip of copper is immersed in dilute nitric acid.
Cu (s) + H+ (aq) + NO3- (aq) => Cu2+ (aq) + NO (g) (or NO2 (g) ) + H2O (l)
b) Potassium permanganate solution is added to an acidic solution of hydrogen peroxide.
MnO4- (aq) + H2O2 (aq) => Mn2+ (aq) + O2 (g) + H2O (l)
c) Concentrated hydrochloric acid is added to solid manganese (II) sulfide.
H+ (aq) + MnS (s) => H2S (g) + Mn2+ (aq)
d) Excess chlorine gas is passed over hot iron filings.
Fe (s) + Cl2 (g) => FeCl3 (s)
e) Water is added to a sample of solid magnesium nitride.
Mg3N2 (s) + H2O (l) => Mg(OH)2 (s) (or Mg2+ (aq) + OH-(aq) ) + NH3 (aq)
f) Excess sulfur dioxide gas is bubbled through a dilute solution of potassium hydroxide.
SO2 (g) + OH-(aq) => HSO3- (aq)
g) Excess concentrated ammonia solution is added to a suspension of silver chloride.
AgCl (s) + NH3 (aq) => Ag(NH3)2+ (aq) + Cl- (aq)
h) Solution of tri-potassium phosphate and zinc nitrate are mixed.
Zn2+ (aq) + PO43- (aq) => Zn3(PO4)2 (s)
Review #4 (1998 AP Exam)
Le Châtelier’s Principle
C(s) + H2O(g) ⇌ CO(g) + H2(g) ΔH°= +131 kJ
A rigid container holds a mixture of graphite pellets (C(s)), H2O(g), and H2(g) at equilibrium. State whether the
number of moles of CO(g) in the container will increase, decrease, or remain the same after each of the following
disturbances is applied to the original mixture. For each case, assume that all other variables remain constant
except for the given disturbance. Explain each answer with a short statement.
a) Additional H2(g) is added to the equilibrium mixture at constant volume.
Decrease moles of CO. H2 is a product; adding product will shift the equilibrium to the left.
b) The temperature of the equilibrium mixture is increased at constant volume.
Increase moles of CO. Because the reaction is endothermic (ΔH° > 0), adding heat (as a reactant) will
shift the equilibrium to the right.
c) The volume of the container is decreased at constant temperature.
Decrease moles of CO. Decreasing V at constant T results in higher P; higher pressure favors the side
with fewer gas molecules. There are twice as many gas molecules on the products side as on the reactants
side. The equilibrium will shift to the left.
d) The graphite pellets are pulverized.
Moles of CO remain the same. Graphite is a solid, and solids do not affect the equilibrium expression.
(The reaction rate may be affected, but that’s not what the question is asking.)