Question

Ellingham diagram is a graphical representation of :

• A. $\Delta G$ vs T
• B. $\Delta H$ vs T
• C. $\Delta G$ vs P
• D. ($\Delta G - T\Delta S$) vs T

Hint:

[Image of Ellingham diagram for various metal oxides] The lower a metal's line sits on the Ellingham diagram, the more stable its oxide is, and the more readily it can reduce the oxides of metals located above it.

Answer 1

The Correct Option is A

The Ellingham diagram is an important tool in metallurgy and thermodynamics, used to understand the behavior of metals and their oxides. This diagram plots the change in Gibbs free energy (\Delta G) against temperature (T), helping in understanding the reduction of metal oxides and the stability of compounds.

Let's analyze the given options to identify the correct representation:

1. \Delta G vs T: This is the correct representation of the Ellingham diagram. It shows the temperature dependence of the stability of compounds, providing insights into which reactions are more favorable at different temperatures.
2. \Delta H vs T: This is not the correct representation. The enthalpy change (\Delta H) vs temperature is not typically used in Ellingham diagrams, as it does not provide sufficient information on the feasibility of reactions.
3. \Delta G vs P: Changes in pressure are not a primary focus in Ellingham diagrams. Such diagrams are primarily concerned with temperature changes and their effects on free energy.
4. (\Delta G - T \Delta S) vs T: Although this expression relates to Gibbs energy, it is not directly used in typical Ellingham diagrams without simplification to \Delta G.

Conclusion: The Ellingham diagram is a plot of \Delta G (Gibbs free energy change) versus temperature (T). Thus, the correct option is \Delta G vs T. This diagram helps predict the conditions required for the reduction of metal oxides in thermodynamic processes.