Question

carbon is not used for reducing aluminium from aluminium oxide,reason why

Answer 1

Reduction of Al2O3 is not performed by carbon due to two primary reasons which are:-

    Very high temperatures around 2100 degree celcius is required for the carbothermic reduction.

   Aluminium Oxide is a very stable oxide and lies below the the oxidation line of carbon in Ellingham Diagram hence Al2O3 cannot be reduced by carbon as it is energetically not favourable.

Any metal will reduce an oxide of another metal that lies above it in an Ellingham diagram. Ex: Al reduces FeO, CrO and NiO in termite reaction but Al will not reduce MgO at a temperature below 1500 0C.

An Ellingham diagram is a graph showing the temperature dependence of the stability for compounds. This analysis is usually used to evaluate the ease of reduction of metal oxides and sulfides. The diagrams are useful in predicting the conditions under which an ore will be reduced to its metal.