Question

Considering Ellingham diagram, which of the following metals can be used to reduce alumina ?

• A. Fe
• B. Mg
• C. Zn
• D. Cu

Answer 1

The Correct Option is B

The Ellingham diagram is a graph that shows the change in Gibbs free energy with temperature for the reactions of oxides, metals, and oxygen. This diagram helps in understanding which metal can be used as a reducing agent to extract another metal from its oxide. The basic principle lying here is that a metal can reduce the metal oxide that lies above it on the Ellingham diagram.

In this question, we need to determine which metal can reduce alumina (\text{Al}_2\text{O}_3). From the Ellingham diagram, we must find a metal that can have a negative free energy change when it reduces alumina, meaning the line for the reducing metal is below that of alumina at the given temperature.

Let's evaluate the options:

1. Fe (Iron): The reduction line for Fe is above that of alumina on the Ellingham diagram, indicating it cannot reduce alumina effectively.
2. Mg (Magnesium): Magnesium's reduction line is below that of alumina, meaning Mg can reduce \text{Al}_2\text{O}_3 effectively. This makes magnesium a suitable reducing agent for alumina.
3. Zn (Zinc): The reduction line for Zn is also above that of alumina, so it cannot be used to reduce alumina.
4. Cu (Copper): Similar to Fe and Zn, Cu's reduction line lies above alumina, indicating it cannot reduce alumina.

Therefore, the correct answer is magnesium (Mg) because its position in the Ellingham diagram relative to alumina indicates it can reduce \text{Al}_2\text{O}_3 effectively.