Predict condition under which Al might be expected to reduce MgO.
Predict condition under which Al might be expected to reduce MgO.
The equation for the formation of two oxides are--
4 Al(s)+3 O2(g)⟶2 Al2O3(s)2Mg(s)+O2(g)⟶2MgO(s)
If we observe the plots for the formation of the two oxides on the Ellingham diagram, we find the two curves intersect each other at a certain point, the corresponding value of △G∘ becomes zero for the reduction of MgO by aluminimum metal.
2MgO(s)+ 4 Al(s)⇌2Mg(s)+ 2 Al2O3(s)
This means that the reduction of MgO by Al metal cannot occur below this temperature (1350°C) . Instead, Mg can reduce Al2O3(s) to Al below
Aluminimum metal (AI) can reduce MgO to Mg above 1350°C because △fG∘ for Al2O3 is less as compared to that of MgO.
3 MgO(s)+ 2 Al(s)T>1350°C−−−−−−→Al2O3(s)+ 3 Mg(s)
Inotherhand, Above 1350°C, the standard Gibbs free energy of formation of Al2O3 from Al is less than that of MgO from Mg. Therefore, above 1350°C, Al can reduce MgO.
The equation for the formation of two oxides are--
4 Al(s)+3 O2(g)⟶2 Al2O3(s)2Mg(s)+O2(g)⟶2MgO(s)
If we observe the plots for the formation of the two oxides on the Ellingham diagram, we find the two curves intersect each other at a certain point, the corresponding value of △G∘ becomes zero for the reduction of MgO by aluminimum metal.
2MgO(s)+ 4 Al(s)⇌2Mg(s)+ 2 Al2O3(s)
This means that the reduction of MgO by Al metal cannot occur below this temperature (1350°C) . Instead, Mg can reduce Al2O3(s) to Al below
Aluminimum metal (AI) can reduce MgO to Mg above 1350°C because △fG∘ for Al2O3 is less as compared to that of MgO.
3 MgO(s)+ 2 Al(s)T>1350°C−−−−−−→Al2O3(s)+ 3 Mg(s)
Inotherhand, Above 1350°C, the standard Gibbs free energy of formation of Al2O3 from Al is less than that of MgO from Mg. Therefore, above 1350°C, Al can reduce MgO.
