What is Ellingham diagharm ? What information can be known from this in the reduction of oxides?

Explanation

The graphical representation of Gibbs energy which provides a sound basis for considering the choice of reducing agent in the reduction of oxides. This graphical representation Is known as Elligham diagram.
`rarr` This diagram helps us in predicting the feasibility of thermal reduction of an ore.
`rarr` The Criterion of feasibility of a reaction is that at a given temperature ,Gibbs energy of the reacation must be negative.
`rarr` Ellingham diagram normally consists plots of `DeltaG^(@)` vs T for formation of oxides of elements .
`rarr` The graph indicates whether a reaction is possible or not , i.e. , the tendency of reducation with a reducing agents is indicated with a reducing agent is indicated.
`rarr` The reducing agent forms its oxide when the metal oxide is reduced. The roel of reducing agent is to make the sum of `DeltaG^(@)` values of the two reactions negative.
`rarr` out of C and CO , carbon monoxide (CO) is a better reducting agent at 673K.
`rarr` At 983K (or) above coke (C) is better reducing agent. ,
`rarr` The above observations are form Ellingham diagam . ,
Zinc is not extracted from zinc oxide through reduction by using CO.
Explanation :
`2Zn+O_(2)rarr 2ZnO,DeltaG^(@)=-650KJ`
`2CO+O_(2)rarr2CO_(2)'DeltaG^(@)=-450KJ`
`2ZnO+2COrarr2Zn,2CO_(2')DeltaG^(@)=200KJ`
`DeltaG^(@)` = positive indicatis that reaction is not feasible.
The above fact is explained on the basis of Ellingham diagram.