Yesterday’s Lab Results (With No
Error!)
Cu2+(aq)
Cu(s)
Fe2+(aq)
Mg2+(aq)
Zn2+(aq)





Fe(s)

Mg(s)


Zn(s)




Cu2+(aq) is identified as the strongest
oxidizing agent (SOA)
 Based on greatest number of
spontaneous reactions
Mg(s) is identified as the strongest
reducing agent (SRA)
 Based on greatest number of
spontaneous reactions
A table of reduction half-reactions is
built to indicate the relative strength
of one OA or RA to another.
The SOA always appears at the
top left of this table
Cu2+(aq) + 2 e− → Cu(s)
Fe2+(aq) + 2 e− → Fe(s)
Zn2+(aq) + 2 e− → Zn(s)
Mg2+(aq) + 2 e− → Mg(s)
Reaction Spontaneity Rule
A spontaneous reaction happens when the
OA is strong enough to remove electrons
from the RA
The relative strength of an OA or RA is
identified by its position in the table
OA
spontaneous
reaction
+
RA
RA
+
OA
non-spontaneous
reaction
Build a table of reduction half-reactions
based on the following observations:
Reactions of Metals with Solutions
of Metal Ions
Be2+(aq) Cd2+(aq) Ra2+(aq)
V2+(aq)
Be(s)




Cd(s)




Ra(s)




V(s)




 indicates a spontaneous reaction
 indicates a non-spontaneous reaction
Redox tables can also be built by
examining the net ionic equation of several
reactions and observations of spontaneity
For each reaction, the OA and RA must be
identified
The order in which they are arranged into a
table is based upon the spontaneity rule
Use the following redox reactions to build a
table of reduction half-reactions:
3 Co2+(aq) + 2 In(s) → 2 In3+(aq) + 3 Co(s)
Cu2+(aq) + Co(s) → Co2+(aq) + Cu(s)
Cu2+(aq) + Pd(s) → no reaction
Use the following equations to build a table
of reduction half-reactions:
3 Sr(s) + 2 Ce3+(aq)
3 Ni(s) + 2 Ce3+(aq)
Ni(s) + 2 H+(aq)
Pt(s) + 4 H+(aq)
spont
non-spont
spont
non-spont
2 Ce(s) + 3 Sr2+(aq)
2 Ce(s) + 3 Ni2+(aq)
H2(g) + Ni2+(aq)
2 H2(g) + Pt4+(aq)