Analyzing the Ellingham diagram for standard free energy of formation of oxides, an abrupt upward ch — Metallurgy and Isolation of Elements Chemistry Question

💡 Solution & Explanation

An abrupt upward slope change in the Ellingham diagram indicates a phase transition (melting or boiling point) of the pure metal. When the metal becomes liquid or gas, its entropy increases, making the entropy change of the oxidation reaction ($M_{(l/g)} + O_{2(g)} \rightarrow MO_{(s)}$) more negative, which steeper the positive slope.