The “Zebra” cell was invented in 1985 in South Africa as part of the “ZEolite Ba
ID: 920536 • Letter: T
Question
The “Zebra” cell was invented in 1985 in South Africa as part of the “ZEolite Battery Research Africa” project, and is used in all-electric municipal buses and other vehicles. It uses nickel and molten sodium as its electrodes. Its overall cell reaction is: NiCl2(l) + 2Na(l) <--> Ni(s) + 2NaCl(l)
a) Write the two half-reactions for this battery.
b) Calculate the Eo for the Zebra cell (show your work).
c) Are the reactants in this battery at room temperature when it is operating? Explain how you know.
Explanation / Answer
a)
NiCl2(l) + 2Na(l) <--> Ni(s) + 2NaCl(l)
Ni2+ + 2 e <---> Ni(s) 0.25
Na+ + e <---> Na(s) 2.71
The most negative will oxidize, then:
Ni2+ + 2 e <---> Ni(s) 0.25
Na(s) <--->Na+ + e +2.71
b)
Apply formula
Ecell = Ered+Eox
Ecell = Ered+Eox = 2.71-0.25 = 2.46
Ecell = 2.46 V
c)
Yes, since they are at room temperature and under 1 atm of pressure (approx)
If this was not the case, all the Ecell will be wrong since those are based on STP conditions
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