- 1. Electrochemistry Electrode Potentials
2. Electrochemistry 1. What are electrode potentials? 3.
Electrochemistry
- Electric potential arising from the separation of charges in
the equilibrium in a redox half equation.
- It is measured with respect to S.H.E.
1. What are electrode potentials? Zn 2+(aq) + 2e Zn(s) Fe 3+(aq)
+ e Fe 2+(aq) 2H +(aq) + e H 2 (g) Cu 2+(aq) + 2e Cu (s) 4.
Electrochemistry 2. What can we know from electrode potentials? 5.
Electrochemistry 2. What can we know from electrode potentials?
- + forward reaction ( reduction ) favoured
- backward reaction ( oxidation ) favoured
- theextentthe reaction is favoured
6. Electrochemistry 3. How can we measure standard electrode
potentials? 7. Electrochemistry
- connect the half cell that you wish to study to the SHE
- You need to be know how to draw the cell setup.
- Things to note when drawing half cell: (1) salt bridge, (2)
voltmeter and (3) ensure all gases, solutions are at standard
conditions.
3. How can we measure standard electrode potentials? 8.
Electrochemistry 4. How can we use standard electrode potentials?
9. Electrochemistry
- to predict whether a redox reaction is feasible when2species
are mixed.
4. How can we use standard electrode potentials? I 2 + Cr 2+
feasible? V 3++ Cu 2+ feasible? 10. Electrochemistry 4. How can we
use standard electrode potentials?
- 1. Identify possible oxidation/ reduction reactions
- Find electrode potentials for these half equations
- Calculate E cell= E red E ox
11. Electrochemistry Galvanic Cells 12. Electrochemistry 5. How
to distinguish anode and cathode? Galvanic Cell 13.
Electrochemistry 5. How to distinguish anode and cathode? Positive
remove electronsReduction Cathode Negative produce
electronsOxidation Anode Electrons flow from A C Galvanic Cell 14.
Electrochemistry 6. How to draw cell diagram? 15. Electrochemistry
6. How to draw cell diagram? Example 16. Electrochemistry 6. How to
draw cell diagram?
- 2. Electrodes at the extreme ends.
- 4. If redox species of the same phase, separate by comma;
different phase by |
Pt (s) | Anode || Cathode | Pt (s) Pt (s) | Fe 2+Fe 3+|| H +H 2|
Pt (s) Pt(s) | Fe 2+ , Fe 3+ (aq) || H + (aq) | H 2 (g) | Pt(s) 17.
Electrochemistry Electrolytic Cells 18. Electrochemistry 7. How to
distinguish anode and cathode? Electrolytic Cell 19.
Electrochemistry 7. How to distinguish anode and cathode? Positive
attract anionsoxidized Anode Negative attract cationsreduced
Cathode Electrons flow from A C Electrolytic Cell 20.
Electrochemistry 8. How to predict what species is discharged?
- 1. Identify all ions in solution (including H 2 O)
- Cations attracted to cathode;
- Anions attracted to anode
- Find electrode potentials for these half equations
- Cathodemore positive or less negative is discharged
- Anodemore negative or less positive is discharged
21. Electrochemistry Calculations (Strategy) Question
willsurelyinvolve 1 or more of the formulas: Q = It = n F I:
current (A) n: moles ofelectrons! t: time ( s ) F: Faradays
constant (96500 C/mol) F = Le L: Avogadros constant e: 1.6 x 10
19C
