Using the `DeltaG^(@)` for the reactions
`{:(C+O_(2)rarrCO_(2),DeltaG^(@)=-395kJ//"mole"),(2Al(l)+3//2O_(2)rarrAl_(2)O_(3)(s),DeltaG^(@)=-1269kJ //"mole"),(Al_(2)O_(3)(s)rarrAl_(2)O_(3)("melt"),DeltaG^(@)=16kJ //"mole"):}`
What is the EMF for the cell reaction
`2Al_(2)O_(3)("melt")+3Crarr4Al(l)+3CO_(2)(g)`
The number of electrons involved in the reaction is 12.

Answer

`-1.14"volt"`

Explanation

`2Al_(2)O_(3)("melt")to2Al_(2)O_(3)(s)" "triangleG_(1)^(@)=-2xx16`
`2Al_(3)O_(3)(s)to4A(l)+3O_(2)(g)" "triangleG_(2)^(@)=2xx1269`
`3C+3O_(2)to3CO_(2)" "triangleG_(3)^(@)=-3xx395`
`2Al_(2)O_(3)("melt")+3Cto4Al(l)+3CO_(2)(g)`,
`triangleG^(@)=triangleG_(1)^(@)+triangleG_(2)^(@)+triangleG_(3)^(@)=-32+2xx1269-3xx395=1321kJ`
`triangleG^(@)=-nFE^(@)implies1321xx10^(3)=-12xxE^(@)xx96500`
`E^(@)=-1.14` volt