Question

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

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

Answer 1

The correct option is A

ΔG = 0 and melting or boiling point of the metal oxide.

Explanation for the correct answer:-

Option (A)

The given diagram is the Ellingham diagram

• This graph consists of plots of $\mathrm{\Delta G}$ vs Temperature for the formation of oxides of elements that is for the reaction.

$2\mathrm{xM}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{M}}_{\mathrm{x}}\mathrm{O}\left(\mathrm{s}\right)$

• At the point of intersection, the $\mathrm{\Delta G}$ value for the respective reaction involved is $0$.
• The sudden increase in the slope in the graph represents the phase change (solid→liquid or liquid→gaseous).
• Hence it is the correct option.

Therefore, option (A) ΔG = 0, and melting or boiling point of the metal oxide is the correct answer.