Assertion (A): In the Ellingham diagram, a sharp change in slope of line is observed for $Mg \righta

Question

Assertion (A): In the Ellingham diagram, a sharp change in slope of line is observed for $Mg ightarrow MgO$ at $\sim 1120^{\circ}C$.\ Reason (R): There is a large change of entropy associated with the change of state.

Professor PC Thomas Classes · Answer

A sharp change in the slope of an Ellingham diagram indicates a phase transition (melting or boiling). Boiling of Mg at ~1120°C significantly alters the entropy ($\Delta S$), radically changing the slope.