Question

A voltaic cell is constructed from a standard Co2+ Co half cell (Eºred = -0.280V) and a standard Ar Al half cell (Ered=-1.660V The anode reaction is: The cathode reaction is: The spontaneous cell reaction is: The cell voltage is

Answer 1

1)

1)

a)

Oxidation takes place on Anode.

The one with smaller Eo value will be oxidised.

So, the anode reaction is:

Al(s) —> Al3+(aq) + 3 e-

b)

Reduction takes place on Cathode.

The one with greater Eo value will be reduced.

So, the Cathode reaction is:

Co2+(aq) + 2e- —> Co(s)

C)

Overall reaction is:

3 Co2+(aq) + 2Al(s) -> 3 Co(s) + 2Al3+(aq)

d)

Eo cell = Eo cathode - Eo anode

= -0.280 V - (-1.660 V)

= 1.38 V

Answer: 1.38 V

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