Question

Which oxide formation according to Ellingham diagram shows a graph with sudden change in slope?

• A. $\mathrm{CO_2}$
• B. $\mathrm{Ag_2O}$
• C. $\mathrm{Al_2O_3}$
• D. $\mathrm{MgO}$

Hint:

Sudden change in slope in Ellingham diagram indicates a phase transition affecting entropy.

Answer 1

The Correct Option is D

Step 1: Understanding Ellingham diagram.
Ellingham diagram represents the variation of Gibbs free energy change ($\Delta G^\circ$) with temperature for oxide formation reactions.

Step 2: Reason for change in slope.
A sudden change in slope occurs when there is a phase change in either reactant or product, such as melting or boiling, which changes entropy.

Step 3: Analysis of given oxides.
For magnesium oxide formation, magnesium undergoes a phase change at higher temperature, leading to a sudden change in slope in the Ellingham diagram.

Step 4: Conclusion.
Hence, the oxide that shows a sudden change in slope is $\mathrm{MgO$}.