Chemistry · Delta G° (Standard Gibbs energy change) and equilibrium constant

toppr Q Type your question At the point of intersection of and curves , \triangl

toppr Q Type your question At the point of intersection of \( A l_{2} U_{3} \) and \( M g O \) curves \( (A), \triangle G^{0} \) becomes zero for the reaction, \( \frac{2}{3} A l_{2} O_{3}+2 M g \rightarrow+\frac{4}{3} A l \) Below this point, magnesium can reduce alumina. Although thermodynamically feasible, Al is not used for reduction of \( M g O \) because:

  • A. temperature required is very highh
  • B. the yields of metal is very low
  • C. the value of \( \triangle G^{0} \) becomes positive
  • D. magnesium is not used as reducing agent for any

Step-by-step solution

At the intersection point of the Al2O3 and MgO curves, ΔG° = 0 for the given reaction. Below this temperature, Mg can reduce Al2O3. For Al to reduce MgO, the reverse reaction must be spontaneous, which requires temperatures above the intersection. This temperature is very high, making the process impractical, so Al is not used despite thermodynamic feasibility.
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