For hydrogen oxygen fuel cell with reaction
`2H_(2)(g)+O_(2)(g) rarr 2 H_(2)O(l)`
`DeltaG_(f)^(c-)(H_(2)O)=-237.2kJ mol^(-1)`. Hence, `EMF` of the fuel cell is

Options

A. `+2.46 V`
B. `-2.46V`
C. `+1.23 V`
D. `-1.23V`

Answer

c

Explanation

Fuel cell reaction is `:`
`2H_(2)(g)+O_(2)(g) rarr 2H_(2)O(l)`
At anode `: 2H_(2)(g)+4overset(c-)(O)H(aq) rarr 4H_(2)O+4e^(-)` `(` Half oxidation `)`
At cathode `:`
`O_(2)(g)+2H_(2)O(l)+4e^(-)rarr 4 overset(c-)(O)H(aq)` `(` Half reduction `)`
`ulbar(Cell reaction : 2H_(2)(g)+O_(2)(g)rarr2H_(2)O(l))`
`:. n_(cell)=4`
`Delta_(r)G^(c-)=2Delta_(f)G^(c-)._((H_(2)o))-2Delta_(f)G^(c-)._((H_(2)O))-2Delta_(f)G^(c-)._((O_(2)))`
`=2(-237.2)kJ mol^(-1)-2xx0-0`
`=2(-237.2k J mol^(-1)`
`Delta_(r)G^(c-)=-nFE^(c-)._(cell)`
`2(-237.2)kJ mol^(-1)=-4xx96500CxxE^(c-)._(cell)`
`:. E^(c-)._(cell)=1.23V`