1. Lesson 3: Spontaneity of Redox Reactions
UNIT 7:
Lesson 3: Spontaneity of Redox Reactions

2. Table of Standard Reduction Potentials
Each half-reaction can go backward or forward, and is thus written using
When a half-reaction is part of a redox reaction, it goes in one direction only and is written using →.
As written on the table, the forward reactions are reductions, and the backward reactions are oxidations.

3. Reactions in an Electrochemical Cell
Suppose you have two half-cells. One contains Zn(s) and Zn2+(aq). The other contains Cu(s) and Cu2+(aq).
The possible half-reactions are:
Cu e Cu and Zn e Zn
Cu2+ has a higher tendency to reduce than Zn2+, so the actual reactions that occur are:
Cu e- → Cu and Zn → Zn e-

4. The Spontaneous Reaction Dance
A reaction will be spontaneous if and only if there is a reactant to be reduced (on the left side) which is above a reactant to be oxidized (on the right side).
Remember the dance: No, no, yes, no!

5. Brain Break!
Spot It!

6. Important Notes
Sometimes a chemical species appears more than once on the chart. Be sure to use the strongest oxidizing and reducing agents available!
All species in the reaction must be present in order for it to occur!

7. Try This:
Predict whether or not a spontaneous reaction will occur when:
Cl2 is mixed with Ag
Sn is mixed with Mn
Ni2+ is mixed with Pb
Write the equation for each spontaneous reaction above.
20 min

8. Homework:
Pg. 199 #8 (a, c, e, etc.) and 14
5 min