An abrupt upward change in the slope (a "kink") of a metal oxide formation line on the Ellingham dia — Metallurgy and Isolation of Elements Chemistry Question

💡 Solution & Explanation

An abrupt upward bend in the Ellingham diagram indicates that the metal has melted or vaporized. The entropy of the pure metal increases drastically. Consequently, the entropy change ($\Delta S$) for the reaction $M_{(l/g)} + O_2 \rightarrow MO_{(s)}$ becomes significantly more negative, steepening the positive slope (since slope = $-\Delta S$).