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Quiz 5 ? Take Home ? 2016

/XX

NAME: _______________________________________

DUE: 12:15 PM Friday April 8th. Answer all of the following questions in the space provided. Show your work,
provide units, and follow the rules of significant figures. Only a random selection of 5 questions will be graded, and the
total for the quiz will be based on which 5. Leaving any question blank will result in a penalty being applied.
1. Assign the oxidation numbers to each atom in the following reaction. Identify the reagents as either the oxidizing or
reducing agent.
3MnO2(s)

+

4Al(s)

3Mn(s)

+

2Al2O3(s)

2. Balance the following oxidation-reduction reaction in acidic solution, using the half-reaction method.
Br-(aq) + MnO4-(aq) Br2(l)

+ Mn2+(aq)

3. Balance the following oxidation-reduction reaction in basic solution, using the half-reaction method.
NO2-(aq) + Al(s) NH3(g) + AlO2-(aq)

4. Sketch the galvanic cell based on the following overall reactions and provide a summary in line notation. Calculate
E?cell , show the direction of electron flow and the direction of ion (KNO3) migration through the salt bridge, identify the
cathode and anode. Assume that all concentrations are 1.0M and that all partial pressures are 1.0 atm and that active
electrodes are in use.
Cu2+(aq) + Mg(s)

Mg2+(aq) + Cu(s

5. Consider only the species (at standard conditions): Na+, Cl-, Ag+, Ag, Zn2+, Zn, Pb
In answering the following questions. Give reasons for your answers.
a. Which is the strongest reducing agent?

b. Which species can be oxidized by HSO4-(aq) in acid?

c. Which species can be reduced by Al(s)

6. Use the table of standard reduction potentials on the data sheet to pick one reagent that is capable of each of the
following (under standard conditions in acidic solutions):
a. reduces Cu2+ to Cu but does not reduce Cu2+ to Cu+.

b. oxidizes Mn to Mn2+ but does not oxidize Ni to Ni2+.

7. Under standard conditions, what reaction occurs, if any, when each of the following operations are performed? For
reactions that occur, calculate E?cell at 25 ?C.
i. Drops of Br2 liquid are added to a solution of NaI.

8. For the following reaction 2MnO4-(aq) +

4H2O(l)

ii. A sliver wire is placed in a solution of CuCl2.

+ 6I-(aq)

Calculate E?cell, ?G?, and K at 25 ?C for the production of I2.

9. Consider the following galvanic cell at 25?C:
Pt(s) | Cr3+(aq) (0.30 M), Cr2+(aq) (2.0 M) || Cu2+(aq) (0.20 M) |Cu(s)
Calculate Ecell under these conditions.

3I2(s) +

2MnO2(s) +

8OH-(aq)