The rusting of iron takes place as follows `:`
`2H^(o+)+2e^(-) +(1)/(2)O_(2)rarr H_(2)O(l)," "E^(c-)=+1.23V`
`Fe^(2+)+2e^(-) rarr Fe(s)," "E^(c-)=-0.44V`
Calculae `DeltaG^(c-)` for the net process.

Options

A. `-322kJ mol^(1)`
B. `-161kJ mol^(-1)`
C. `-152kJ mol^(-1)`
D. `-76kJ mol^(-1)`

Answer

a

Explanation

Reactions`:`
`i. Fe(s) rarr Fe^(2+)+2e^(-)+2e^(-), E^(c-)=+0.44V`
and `DeltaG^(c-)._(1)=-nE^(c-)F=-2xx0.44xxF`
`ii. 2H^(o+)+2e^(-)+(1)/(2)O_(2)rarr H_(2)O(l), " "E^(c-)=+1.23V`
and `Delta^(c-)._(2)=-2xx(+1.23)xxF`
Net reaction `:`
`Fe(s)+2H^(o+)+(1)/(2)O_(2)rarr Fe^(2+)+H_(2)O(l)`
`DeltaG^(c-)._(3)=DeltaG^(c-)._(1)+G^(c-)._(2)`
`=-2xx(+0.44)xxF+(-2xx1.23xxF)`
`=-0.88F-2.46F=-3.34F`
`=-3.34xx96500J`
`=-323.32kJ~~_3.34kJ`