Answers to FRQ Unit test on Chemical reactions
2003 C
(a) A solution of potassium phosphate is mixed with a solution of calcium acetate.
PO43– + Ca2+  Ca3(PO4)2
(b) Solid zinc carbonate is added to 1.0 M sulfuric acid.
ZnCO3 + H+  Zn2+ + H2O + CO2
(c) A solution of hydrogen peroxide is exposed to strong sunlight.
H2O2  H2O + O2
(d) A 0.02 M hydrochloric acid solution is mixed with an equal volume of 0.01 M calcium
hydroxide.
OH– + H+  H2O
(e) Excess concentrated aqueous ammonia is added to solid silver chloride.
NH3 + AgCl [Ag(NH3)2]+ + Cl–
(f) Magnesium ribbon is burned in oxygen.
Mg + O2  MgO
(g) A bar of strontium metal is immersed in a 1.0 M copper(II) nitrate solution.
Sr + Cu2+  Cu + Sr2+
(h) Solid dinitrogen pentoxide is added to water.
N2O5 + H2O  H+ + NO3–
2004 C
(a) A solution of copper(II) sulfate is spilled onto a sheet of freshly polished aluminum metal.
Al + Cu2+  Cu + Al3+
(b) Dimethyl ether is burned in air.
(CH3)2O + O2  H2O + CO2
(c) A 0.1 M nitrous acid solution is added to the same volume of a 0.1 M sodium hydroxide
solution.
HNO2 + OH–  H2O + NO2–
(d) Hydrogen iodide gas is bubbled into a solution of lithium carbonate.
HI + CO32–  H2O + CO2 + I–
(e) An acidic solution of potassium dichromate is added to a solution of iron(II) nitrate.
2–
H+ + Cr2O7 + Fe2+  H2O + Cr3+ + Fe3+
(f) Excess concentrated aqueous ammonia is added to a solution of nickel(II) bromide.
NH3 + Ni2+  [Ni(NH3)4]2+
(g) A solution of sodium phosphate is added to a solution of aluminum nitrate.
PO43– + Al3+  AlPO4
(h) Concentrated hydrochloric acid is added to a solution of sodium sulfide.
H+ + HS–  H2S OR H+ + S2–  H2S
2005 C
(a) A strip of zinc is placed in a solution of nickel(II) nitrate.
Zn + Ni2+  Ni + Zn2+
(b) Solid aluminum hydroxide is added to a concentrated solution of potassium hydroxide.
Al(OH)3 + OH–  Al(OH)4– OR Al(OH)63–
(c) Ethyne (acetylene) is burned in air.
C2H2 + O2  H2O + CO2
(d) Solid calcium carbonate is added to a solution of ethanoic (acetic) acid.
CaCO3+ CH3COOH  H2O + CO2 + Ca2+ + CH3COO–
(e) Lithium metal is strongly heated in nitrogen gas.
Li + N2  Li3N
(f) Boron trifluoride gas is added to ammonia gas.
BF3 + NH3  BF3NH3
(g) Sulfur trioxide gas is bubbled into a solution of sodium hydroxide.
SO3 + OH–  H2O + SO42–
(h) Equal volumes of 0.1 M solutions of lead(II) nitrate and magnesium iodide are combined.
Pb2+ + I–  PbI2
2006 C
(a) Solid potassium chlorate is strongly heated.
KClO3  KCl + O2
(b) Solid silver chloride is added to a solution of concentrated hydrochloric acid.
AgCl + Cl–  [AgCl2]–
(c) A solution of ethanoic (acetic) acid is added to a solution of barium hydroxide.
CH3COOH+ OH–  CH3COO– + H2O
(d) Ammonia gas is bubbled into a solution of hydrofluoric acid.
NH3 + HF  NH4+ + F–
(e) Zinc metal is placed in a solution of copper(II) sulfate.
Zn + Cu2+  Cu + Zn2+
(f) Hydrogen phosphide (phosphine) gas is added to boron trichloride gas.
H3P + BCl3  H3PBCl3
(g) A solution of nickel(II) bromide is added to a solution of potassium hydroxide.
Ni2+ + OH–  Ni(OH)2
(h) Hexane is combusted in air.
C6H14 + O2  CO2 + H2O