Q.Using the Ellingham diagram,
(A) Predict the conditions under which
(B) it is possible to reduce Fe₂O₃ by coke at a temperature around 1200 K
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Start your 14-day free trial to unlock the full solution →Step 1 -- the governing rule. On the Ellingham diagram, a metal can reduce the oxide of any other metal whose formation line lies ABOVE its own (i.e. whose oxide is LESS stable); the lower line at a given temperature is always the more stable oxide.
Step 2 -- (A)(i) Al reducing MgO. On Figure 1.4, the 2Mg+O2=2MgO line lies BELOW the 4/3Al+O2=2/3Al2O3 line across the plotted range -- MgO is the MORE stable oxide. Since aluminium's own line sits above magnesium's, aluminium cannot supply a lower-energy oxide than MgO, so aluminium CANNOT reduce magnesia under these conditions.
Step 3 -- (A)(ii) Mg reducing Al2O3. This is the reverse comparison: because MgO's line lies below Al2O3's, magnesium's oxide IS the more stable one, so magnesium metal CAN reduce alumina, taking the oxygen away from aluminium to form MgO while liberating Al. …
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