Spontaneous redox reaction

Question

Determine the anode, cathode and overall cell potential for the following spontaneous redox reactions.

Sn2+/Sn, Ag+/Ag

&

Na+/Na, Br2/Br-

Answer 1

Looking up standard reduction potentials, one finds the following:

Sn²⁺ + 2e^- ==> Sn  Eº = -0.14 V

Ag⁺ +1e^- ==> Ag  Eº = 0.80 V

Anode will be Sn

Cathode will be Ag

Overall cell potential will be 0.80 - (-0.14) = 0.94 V

 

Couldn't easily find reduction potential for Na, but it will be rather low and Br2 is rather high, so

anode will be Na

cathode will be Br₂

overall potential:  find value for Na and subtract it from that for Br₂