Chemistry 162. Test Four. May 02, 2014. Name ________________________________________________
F = 96485 C/mol
G = RT ln(Q/K)
Go = -nFEo
Part One. Seventeen points (each question is two points)
_____ 1) Which of the following is true for a galvanic (voltaic) cell?
1- The electron flow is from the positive electrode to the negative electrode.
2- The electron flow is from the anode to the cathode.
3- The electron flow is from oxidizing agent to the reducing agent through an external circuit.
a- 1 only
b- 1 and 2 only
c- 2 only
d- 3 only
_____ 2) What is the reduction potential for the following nonstandard half-cell?
Pt | IO1- (0.30 M), l1- (0.60 M), OH- (0.46 M) ||
a- 0.48 V
b- 0.52 V
c- 0.50 V
d- 0.31 V
_____ 3) What is the potential for the cell Pt | ClO2- (aq), ClO31- (aq), OH- (aq) || Hg2+ (aq) | Hg
a- 0.50 V
b- 0.16 V
c- 0.21 V
d- 0.55 V
_____ 4) For the following pairs – Cl2 (g) and ClF (g) , PbBr2(g) and PbBr2(liq)– which species have the highest entropies?
a- Cl2 (g) and PbBr2(liq)
b- ClF (g) and PbBr2(liq)
c- ClF (g) and PbBr2(g)
d- Cl2 (g) and PbBr2(g)
_____ 5) For the following reaction
Br2(l) → 2 Br(g)
a- H is - and S is - for the reaction
b-H is + and S is - for the reaction
c-H is + and S is + for the reaction
d-H is - and S is + for the reaction
_____ 6) For a reaction Ho = -76.0 kJ and So = -234 J/K. If n=3, find Eo at 25.0 oC.
a- 0.192 V
b- 0.022 V
c- 0.065 V
d- 0.032 V
_____ 7) For the system, 4 OH- → O2 + 2 H2O + 4 e-, how many moles of O2 can be produced from a solution that was
electrolyzed for 6.00 hr using a current of 8.00 amps?
a- 0.224
b- 0.448
c- 0.896
d- 4.48 x 10-2
Part Two.
1) (15 points) Definitions.
First Law of Thermodynamics
Second Law of Thermodynamics
Third Law of Thermodynamics
Oxidation
Reduction
2) (6 points) Balance the following equation under basic conditions. Show the half reactions under the proper conditions
and label them as oxidation and reduction. Show the final balanced equation.
BrO3-(aq)
+
MnO2(s)
→
MnO4-(aq) +
Br-(aq)
3) (10 points) For the following cell find Go and K?
C |Cu2+(aq), Cu1+(aq) || H+(aq) | O2(g) | Pt
4) (10 points) What is the potential for the following cell?
Mn(s) | Mn2+(1.5 x 10-3 M) || Fe3+ (2.00 M) | Fe(s)
5) (10 points) From the tabular data given, find Horxn, Sorxn, Gorxn, and K for each of the following at 25 oC.
H2(g)
+
Fe2O3(s)
Na2CO3(aq)
+
2 HBr(aq)
→

Fe (s)
NaBr(aq)
6) (7 points) Consider the reaction:
CO2(g) + CCl4(g) 
2 COCl2(g)
Calculate G for this reaction at 25.0 oC under the following conditions.
[CO2] = 4.58 x 10-3 M
[CCl4] = 7.11 x 10-3 M
[COCl2] = 3.04 x 10-2 M
+
+
H2O(l)
H2O(g)
+
CO2(g)