1. Unit Fourteen: Redox Reactions
Day Four

2. Activity Series

3. Activity Series
A listing of metals (and hydrogen) in order of decreasing activity, decreasing ability to oxidize, and decreasing tendency to lose electrons
The metals at the top of the series have the greatest tendency to lose electrons, more easily oxidized, and are more reactive.
The metals at the bottom of the series have the greatest tendency to accept electrons, more easily reduced, and are less reactive.

4. Practice Problems
Arrange Zn, Cu, and Fe in order of decreasing ease to oxidize and write their oxidation half reactions
Zn > Fe > Cu
Zn(s) →
Fe(s) →
Cu(s) →
Zn2+(aq) + 2e-
Fe2+(aq) + 2e-
Cu2+(aq) + 2e-

5. Sometimes it is more convenient to think in terms of reduction
Sometimes it is more convenient to think in terms of reduction. Write the reduction half reactions in order of best reducer to worst reducer.
→ Cu(s)
→ Fe(s)
→ Zn(s)
Cu2+(aq) + 2e-
Fe2+(aq) + 2e-
Zn2+(aq) + 2e-

6. Activity Series
Each reaction in the Activity Series is an oxidation half reaction.
The half reactions at the top are most likely to occur in the forward direction.
The half reactions at the bottom are most likely to occur in the reverse direction.
Any half reaction on the list will be spontaneous when paired with the reverse of any half reaction below it. (Like the picture above to the left)

8. Will the following redox reactions be spontaneous?
Mn(s) + Ni2+(aq) → Mn2+(aq) + Ni(s)
YES
Fe(s) + Mg2+(aq) → Fe2+(aq) + Mg(s) NO
Fe(s) + Pb2+(aq) → Fe2+(aq) + Pb(s)
Zn(s) + Ni2+(aq) → Zn2+(aq) + Ni(s)
Zn(s) + Ca2+(aq) → Zn2+(aq) + Ca(s)

9. Metals above H2 on the activity series will dissolve in acids, while metals below H2 will not dissolve in acids. Practice Problems: Will the following metals dissolve in an acid?
Zinc
YES
Silver NO
Gold
Lead
YES
Copper NO