Question

Observe the following Ellingham diagram, and identify the incorrect statement regarding it:

• A. At point ‘A’ for the reduction of Al\textsubscript{2}O\textsubscript{3} by Mg, \(\Delta G^\circ = 0\)
• B. Below 1673K, Mg can reduce Al\textsubscript{2}O\textsubscript{3} to Al
• C. Below 1673K, Al can reduce MgO to Mg
• D. Above 1673K, Al can reduce MgO to Mg

Hint:

In Ellingham diagrams, the lower the line, the better the reducing agent. Use this to determine feasibility of reduction.

Answer 1

The Correct Option is C

Ellingham diagrams represent the temperature dependence of the stability of compounds. A metal can reduce the oxide of another metal if its line lies below the other's in the diagram. Below 1673K, Mg line lies below Al, so Mg can reduce Al\textsubscript{2}O\textsubscript{3}, not the other way around. The statement that Al reduces MgO is incorrect.