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According to the Ellingham diagram, which of the following metals can reduce chromium oxide ( \mathrm{Cr}_2 \mathrm{O}_3 ) at 1500^{\circ} \mathrm{C} ?

Option: 1

Iron (Fe)

Option: 2

Silver (\mathrm{Ag})

Option: 3

Copper \mathrm{ (Cu)}

Option: 4

Aluminium \mathrm{(Al)}

Answers (1)


According to the Ellingham diagram, which depicts the thermodynamic stability of oxides at various temperatures, the metals that can reduce chromium oxide \left(\mathrm{Cr}_2 \mathrm{O}_3\right) at 1500^{\circ} \mathrm{C} are those located below the chromium line.

At 1500^{\circ} \mathrm{C}, Aluminium(Al) is positioned below the chromium line, indicating that it has lower free energy of formation for its oxide compared to chromium oxide at 1500^{\circ} \mathrm{C}. This means that Aluminium(Al) is thermodynamically capable of reducing chromium oxide.

On the other hand, iron (Fe), silver (Ag), and copper (Cu) are positioned above the chromium line on the Ellingham diagram. This suggests that they have higher free energies of formation for their respective oxides compared to chromium oxide. Therefore, these metals are not capable of reducing chromium oxide at that temperature.
Hence, the correct option is 4. 

Posted by

Ritika Kankaria

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