Write electrode reaction and net cell reaction for fuel cell. Calculate e.m.f. of the following cell at 25 °C.
Standard reduction potential (SRP) of Zn and Cu are − 0.76 V and 0.334 V respectively
Cell reactions for fuel cell:
1) Oxidation at anode (−):
At anode, hydrogen gas is oxidized to H2O.
2H2(g) + `4OH_(aq)^-` → 4H2O(l) + 4e−
2) Reduction at cathode (+):
The electrons released at anode travel to cathode through the external circuit.
Here O2 gas is reduced to OH−
O2(g) + 2H2O(l) + 4e− → `4OH_((aq))^-`
3) Net cell reaction
The overall cell reaction is the sum of oxidation at anode and reduction at cathode.
4) Calculation of e.m.f.:
`E_(Cu)^0` = 0.334 V
`E_(Zn)^0` = −0.76 V
The overall cell reaction is the redox reaction which is the sum of oxidation half reaction at anode and reduction half reaction at cathode.
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