Chemistry II – AP
Chapter 20 – Electrochemistry
Test format
14 multiple choice (2 points each)
5 multiple choice (4 points each)
1 free response (12 points each)
TEST – Tuesday, April 28, 2009
(60 points total)
Multiple Choice topics:
 Balancing redox reactions in acid or base solution
o Knowledge of oxidation numbers
o Recognizing what element is oxidized/reduced
o Recognizing what substance is the oxidizing agent/reducing agent
o Knowing the steps to balance half-reactions, and adding together
 Standard reduction potential table (given on the AP equations sheet)
o Be able to predict what is the best oxidizing agent/reducing agent from the table
o Be able to calculate Ecell values for a given electrochemical cell
o Be able to determine what can oxidize/reduce ___ (using the table as reference)
 For example; What is capable of reducing Cu2+ to Cu?
 Voltaic cells (galvanic cells)
o Spontaneous reactions (positive Ecell)
 Be able to calculate Ecell
 Number of electrons transferred in balanced overall reaction
o Electrons flow from the anode to the cathode
o Anode half-cell
o Cathode half-cell
 Metal in metal solution (usually)
 Metal in metal solution (usually)
 Oxidation, loss of electrons
 Reduction, gain of electrons
 If metal electrode, it loses mass
 If metal electrode, gains mass
 [M+] increases in solution
 [M+] decreases in solution
 Electrode is labeled negative
 Electrode is labeled positive
o Salt bridge
 Direction of flow of the positive and negative ions
 Gibb’s free energy/ Cell potential relationship (G = -nFEcell)
 Nernst equation
o Be able to use to calculate Ecell for nonstandard conditions
o Given Ecell, be able to solve for a concentration
 Electrolysis
 Molten NaCl (or other ionic compounds)
 Aqueous NaCl (or other ionic compounds)
 Water (with an electrolyte present)
 Electroplating of a metal
o Qualitative descriptions
 What’s happening at the anode/cathode, etc.
o Quantitative calculations
 How much metal is reduced when 2.50 A is applied for 2 hours…
 How much time is needed to …
 What current is needed to …
Free Response problem
 From an old AP chemistry exam
o Electrochemical cell
 Half-reactions, overall reaction, standard cell potential
o Electrolysis calculations
o Gibb’s free energy calculation
o Use of Nernst equation To calculate Ecell for nonstandard conditions