Thefree energiesof formation( Delta_fG )of MgO(s) and CO(g) at1273 Kand2273 Krepectivelyare givenbelow :Delta _f[ Mg O (s)] =-941 kJ mol^(-1)at1273 KDelta_fG [MgO (s)] =- 314 kJ mol ^(-1)at 2273 KDelta _fG [CO (g) ] =-439 kJ mol ^(-1)at1273 KDelta _fG [CO (g)]=-628 kJmol^(-1) at2273 KOnthebasis of abovepredictthe temperature at which carboncan beusedas areducingagentforMgO(s).

Thefree energiesof formation( Delta_fG )of MgO(s) and CO(g) at1273 Kan

1.	Thefree energiesof formation( Delta_fG )of MgO(s) and CO(g) at1273 Kand2273 Krepectivelyare givenbelow :Delta _f[ Mg O (s)] =-941 kJ mol^(-1)at1273 KDelta_fG [MgO (s)] =- 314 kJ mol ^(-1)at 2273 KDelta _fG [CO (g) ] =-439 kJ mol ^(-1)at1273 KDelta _fG [CO (g)]=-628 kJmol^(-1) at2273 KOnthebasis of abovepredictthe temperature at which carboncan beusedas areducingagentforMgO(s).
Answer» Solution :The EQUATIONFOR reductionofMgO by carbon MAYBE writtenas `MgO (s)+C (s)to M g O (s)+CO (g) ` Thefreeenergy`(Delta _ R G ) `oftheabove reaction attwodifferenttemperaturemay becalculatedas follows : ` ""Delta _ rG=Delta_f G [CO (g) ] - Delta _fG [MgO (s)] ` At 1273 K,`"" Delta _ rG=-439 -(-941) = +502 kJ mol ^(-1) ` At2273 K,` "" Delta_rG =-623-(-314) =-314 kJ mol^(-1) ` Since ` Delta_r G `is- veat2273 K,therefore , carboncan be usedasareducing AGENT forMgOat2273K.