Question

Free energy change of $Hg$ and $Mg$ for the conversion of oxides, the slope of $\Delta G$ vs $T$ has been changed above the boiling point of the give metal because:

• A. the entropy is increased
• B. the metal becomes thermally stable
• C. the entropy change is equal to zero
• D. None of the above

Answer 1

The correct option is A the entropy is increased

In Ellingham diagram, all free energy follows straight line unless the material melt or vapourise.
When there is large change in entropy associated with change in state, there will be positive increase in the slope.

Free energy change of $Hg$ and $Mg$ for the conversion of oxides, the slope of $\Delta G$ vs $T$ has been changed above the boiling point of the given metal because above the boiling point of the given metal the entropy is increased.

$\Delta G=\Delta H-T\Delta S$
For plot of ${\Delta }_{f}GvsT,$ , the slope is $-\Delta S$.