Download ELECTROCHEMISTRY REVIEW SHEET

ELECTROCHEMISTRY REVIEW SHEET
1. Assign oxidation numbers to the atoms within the following compounds.
a. KMnO4
K: _____
Mn: _____
O: _____
b. NaClO2
Na: _____
Cl: _____
O: _____
c. NH4+
N: _____
H: _____
d. Zn(CN)2
Zn: _____
C: _____
N: _____
2. Draw the setup for the given cell diagram in the space below. Label the anode
and cathode and draw the direction of electron flow and ion flow. Where does
oxidation occur? Where does reduction occur? Use equations to exemplify.
Voltaic:
Fe (s) | Fe2(SO4)3 (aq) || MnSO4 (aq) | Mn (s), E˚ = 1.632 V
3. Redraw the above cell, changing it to an electrolytic cell. Label the anode and
cathode and draw the direction of electron flow and ion flow. Where does
oxidation occur? Where does reduction occur? Use equations to exemplify.
4. Draw cell diagrams for the following voltaic cell half – reactions.
a.
Mo3+ (aq) + 3 e– → Mo (s)
b.
Pb (s) → Pb2+ (aq) + 2 e–
2+
–
Ni (s) → Ni (aq) + 2 e
Po4+ (aq) + 4 e– → Po (s)
5. Balance these equations using the half – reaction method, identify the species
being oxidized and reduced, and identify the oxidizing agent and reducing agent.
a. Aqueous potassium permanganate reacts with solid nickel in the presence
of hydrochloric acid to synthesize manganese (IV) oxide and several other
products.
b. H3AsO4 (l) + Ag (s) + HOCN (aq) → HAsO2 (l) + AgOCN (aq) + H2O (l)
6. Calculate the standard cell potential and Gibb’s Free Energy for the reactions in
number 5. Are the reactions spontaneous or nonspontaneous? Which would need
to be placed in an electrolytic cell to work?
a.
b.
7. A __________ dry cell is used in C and D batteries that are used in flashlights.
Smaller electronic devices require _______________ batteries like AA and AAA
batteries. Hearing aids, calculators and camera flashes require even smaller
batteries like _______________ batteries. In __________ __________, the
reactants are continuously supplied and products are continuously removed. The
final product of the hydrogen fuel cell is __________.
8. Describe how a key could be gold plated.
9. Describe how a AA or AAA rechargeable battery works.
10. Using the Nernst Equation, calculate the cell potential using the given
information.
a. Ga (s) | GaCl3 (0.10 M) || HgCl2 (0.050 M) | Hg (l)
b.
2 Md(ClO3)3 (aq) + 2 NH4OH (l) → 2 Md (s) + N2 (g) + 2 H2O (l) + 6 HClO3 (aq)
[Md(ClO3)3] = 0.055 M, [HClO3] = 0.010 M, [NH4OH] = 0.100 M.