Question

The point of intersection and sudden increase in the slope, in the diagram given below respectively, indicates:

• A. $\Delta G=0$ and melting or boiling point of the metal oxide.
• B. $\Delta G<0$ and decomposition of the metal oxide.
• C. $\Delta G=0$ and reduction of the metal oxide.
• D. $\Delta G>0$ and decomposition of the metal oxide.

Answer 1

The correct option is A

$\Delta G=0$ and melting or boiling point of the metal oxide.

The given diagram is Ellingham Diagram.

It normally consists of plots of ΔG vs Temperature for formation of oxides of elements i.e., for the reaction,
$2xM\left(s\right)+O2\left(g\right)\to 2M_{x}O\left(s\right)$

At the point of intersection, $\Delta G=0$ for involved reaction.
The sudden increase in slope represent change in phase (solid→liquid or liquid→gaseous).
Hence, option (a) is corr3ect.