Question

Ellingham diagram for metal–oxide system doesn’t give idea about:

• A. Kinetics of the oxidation reaction
• B. Oxidation of metals
• C. Value of partial pressure of oxygen for the reactions shown in a diagram
• D. Reduction of metal oxides

Hint:

Ellingham diagrams help assess thermodynamic feasibility (via \( \Delta G \)) but not reaction kinetics or actual gas pressures like \( p_{O_2} \).

Answer 1

The Correct Option is C

Step 1: What is an Ellingham Diagram?
An Ellingham diagram plots the standard Gibbs free energy change (\( \Delta G^\circ \)) for various oxidation reactions (mostly metal to metal oxide) versus temperature. It is primarily used in metallurgy to predict the feasibility of reduction reactions. Step 2: Information Provided
From an Ellingham diagram, you can infer: - The temperature above which one metal can reduce the oxide of another metal. - The stability of oxides. - Thermodynamic feasibility (not kinetics). Step 3: What It Does Not Show
- It does not provide information about the rate (kinetics) of the reaction. However, this is still sometimes misunderstood as being partially inferable. - Importantly, it does not give the exact partial pressure of oxygen unless extra data is provided or derived. The diagram shows \( \Delta G^\circ \) trends but not actual gas pressures. Conclusion: The Ellingham diagram does not provide direct information about the value of partial pressure of oxygen, making option (3) correct.