Mr. Hom Tanks has just survived an airplane crash and found himself alone on a deserted             island in the Pacific ocean. He finds some materials from the plane and the cargo on the                beaches of the island, and he needs to find how to survive until he is rescued. Luckily, Mr.             Tanks finds large shipments of lots of metal plates (Ni, Pt, and Au), wires, weather balloons,           batteries. 

Q1. Magnetic Properties. Mr. Tanks finds a box of Ni sheets, and he remembers that Ni is         some kind of magnetic material. He cannot remember if it is ferromagnetic or ferrimagnetic. He    becomes excited because thinks that means that he can use the Ni as a permanent magnet. A    permanent magnet could possibly be used to construct a compass to navigate or to construct a    motor/generator.

Explain the key differences between the ferromagnetic and ferrimagnetic materials based on our   introduction. State, if a material is ferromagnetic, is it always a strong magnet? [6 Points]

Q2.  Electrochemistry I, HER. Mr. Tanks has another idea that if he can make one or more     large and loud explosions when there is a passing ship, then someone will come to rescue him. To accomplish this, he wants to make and store a large amount of hydrogen in some big           balloons he found.

(Warning: Do not make hydrogen at home. It can be very dangerous!)

i) Based on the introduction in this course, propose a suitable pair of oxidation and  reduction processes that could be used at an anode and cathode to make hydrogen from water. State or label which process should happen on the cathode and which  process should happen on the anode. [7 points]

ii) Assume the standard cell potential of Mr. Tanks’ process for making hydrogen from    water is EO  = - 1.2 V. State if it better to drive the reaction with 2 battery in parallel with   1.2 V of potential or two batteries in series with 2.4 V of potential. Explain why. [6 Points] (Hint: Consider what electrochemical concepts we introduced could be relevant. Why     could more potential be helpful or not helpful?)

Q3 Electrochemistry II, ORR. Mr. Tanks is very thirsty, and he cannot directly drink the water on the island. He has the idea that he can use the oxygen reduction reaction to make drinking water from O2 in the air.

In lecture, the half reaction we introduced for ORR is:

O2 + 4e¯ + 4H+ t 2H2O (In Acid)

Assume that ORR performance is governed by the following volcano diagram:

i) If Hom Tanks can choose between Ni, Pt, and Au, state which metal is most suitable for ORR? [3 Points] (Hint: Just state.)

ii) Assume that after a lot of effort that Mr. Tanks somehow assembles a crude electrochemical  cell to make H2O. This cell has ORR at the cathode and HOR (hydrogen oxidation) at the anode (using the hydrogen he made earlier) with standard reduction potentials as follows:

2H+ + 2e¯ t 工2

O2 + 4e¯ + 4H+ t 2H2O

(0.00 V)

(+1.23V)