South Pasadena • Honors Chemistry
Name
5 • Chemical Reactions
Period
5.3
PROBLEMS
1. For each of the following reactions, determine
whether it is a redox process. If so, identify the
elements that are oxidized and reduced.
(a) 8 Ca (s) + S8 (g)  8 CaS (s)
Redox?
Yes
No
Ca is oxidized from 0 to +2.
S is reduced from 0 to ‒2.
(b) CaCl2 (aq) + AgNO3 (aq) 
Ca(NO3)2 (aq) + AgCl (s)
Redox?
Yes
__________ is reduced from ____ to ____.
(c) CaO (s) + H2O (ℓ)  Ca(OH)2 (aq)
Yes
No
__________ is oxidized from ____ to ____.
__________ is reduced from ____ to ____.
(d) 2 Al (s) + 3 CuCl2 (aq) 
3 Cu (s) + 2 AlCl3 (aq)
Redox?
Yes
REDOX
No
Al is oxidized from 0 to +3.
Cu is reduced from +2 to 0.
(e) 2 MgO (s)  2 Mg (s) + O2 (g)
2. Predict the products and write the balanced
equation for each reaction. Then identify the
element that is oxidized and reduced, and write the
half-reactions.
(a) Aluminum metal is placed in a solution of lead
nitrate.
Balanced Molecular Equation:
2 Al (s) + 3 Pb(NO3)2 (aq) 
3 Pb (s) + 2 Al(NO3)3 (aq)
Net Ionic Equation:
2 Al (s) + 3 Pb2+ (aq)  3 Pb (s) + 2 Al3+ (aq)
Oxidation Half-Reaction:
Al  Al3+ + 3 e‒
Reduction Half-Reaction:
Pb2+ + 2 e‒  Pb
(b) Magnesium metal is placed in a solution of
nickel chloride.
Balanced Molecular Equation:
Mg (s) + NiCl2 (aq)  Ni (s) +MgCl2 (aq)
Net Ionic Equation:
Mg (s) + Ni2+ (aq)  Ni (s) + Mg2+ (aq)
Oxidation Half-Reaction:
Redox?
Yes
REACTIONS
No
__________ is oxidized from ____ to ____.
Redox?
–
Date
No
O is oxidized from ‒2 to 0.
Mg is reduced from +2 to 0.
Mg  Mg2+ + 2 e‒
Reduction Half-Reaction:
Ni2+ + 2 e‒  Ni
(c) Chlorine gas is bubbled in a solution of
potassium bromide.
(f) Copper metal is placed in a solution of silver
nitrate. (Copper(II) is formed.)
Balanced Molecular Equation:
Balanced Molecular Equation:
Cl2 (g) + 2 KBr (aq)  Br2 (ℓ) + 2 KCl (aq)
Cu (s) + 2 AgNO3 (aq) 
2 Ag (s) + Cu(NO3)2 (aq)
Net Ionic Equation:
Net Ionic Equation:
Cl2 (g) + 2 Br‒ (aq)  Br2 (ℓ) + 2 Cl‒ (aq)
Cu (s) + 2 Ag+ (aq)  2 Ag (s) + Cu2+ (aq)
Oxidation Half-Reaction:
2 Br‒  Br2 + 2 e‒
Oxidation Half-Reaction:
Cu  Cu2+ + 2 e‒
Reduction Half-Reaction:
Cl2 + 2 e‒  2 Cl‒
Reduction Half-Reaction:
Ag+ + e‒  Ag
(d) Zinc metal is placed in a solution of
hydrochloric acid.
(g) Sodium metal is placed in water. (Hint: write
water as HOH.)
Balanced Molecular Equation:
Balanced Molecular Equation:
Zn (s) + 2 HCl (aq)  H2 (g) + ZnCl2 (aq)
2 Na (s) + 2 H2O (ℓ)  H2 (g) + 2 NaOH (aq)
Net Ionic Equation:
Net Ionic Equation:
Zn (s) + 2 H+ (aq)  H2 (g) + Zn2+ (aq)
Na (s) + 2 H2O (ℓ) 
H2 (g) + 2 Na+ + OH‒ (aq)
Oxidation Half-Reaction:
Zn  Zn2+ + 2 e‒
Oxidation Half-Reaction:
Reduction Half-Reaction:
Na  Na+ + e‒
2 H + 2 e  H2
+
‒
Reduction Half-Reaction:
(e) Iron metal is placed in a solution of copper(II)
sulfate. (Iron(III) is formed.)
2 H+ + 2 e‒  H2
Balanced Molecular Equation:
2 Fe (s) + 3 CuSO4 (aq) 
3 Cu (s) + Fe2(SO4)3 (aq)
Net Ionic Equation:
2 Fe (s) + 3 Cu2+ (aq)  3 Cu (s) + 2 Fe3+ (aq)
Oxidation Half-Reaction:
Fe  Fe3+ + 3 e‒
Reduction Half-Reaction:
Cu2+ + 2 e‒  Cu
3.