Ellingham Diagrams.

 Plot  DG_deg  of oxide versus temperature => gradient = -DS_deg
 

- Linear (almost) except for kinks at phase changes

 cf. Mg, Zn lines
 

Use for extraction of metals.

 - If line is above those involving carbon, the metal oxide can be reduced.

 - C + O₂  CO₂ entropically neutral =? flat.

 - 2CO + O₂  2CO₂

 - At 983K: For FeO: below 983K only CO reduces FeO

 above 983K, CO and C reduce FeO

 => easier to get coke than CO  so therefore we work at 1000K
 

-Above 1400K, C + O₂  CO can reduce Cr₂O₃

 => Cr₂O₃/FeO/C at 1400K so we get blue steel

 
- Zn, Fe, Pb made using C as reducing agent.

 - Not MgO, or Al₂O₃

Copyright Dr. D. O'Hare 1996.