What chemical principle isinvolvedin choosing a reducingagent for gettingthe metalfrom itsoxideore ? Considerthe metaloxides Al_2O_3 andFe_2O_3 , andjustifythe choiceof thereducingagent.

What chemical principle isinvolvedin choosing a reducingagent for gett

1.	What chemical principle isinvolvedin choosing a reducingagent for gettingthe metalfrom itsoxideore ? Considerthe metaloxides Al_2O_3 andFe_2O_3 , andjustifythe choiceof thereducingagent.
Answer» Solution :Thechemicalprincipleinvolvedin thereducing of metaloxidestometalsis THATAT any giventemperature,any metal will reducetheoxideof othermetalswhich lie aboveit intheEllinghamdiagram. This isbecuasethe standard free ENERGY CHANGE (`Delta_rG^(@)` ) ofthecombinedredox reactionwill be- ve by an amountequal tothe difference in` Delta_f G^(@) `ofthetwometaloxides atthat temperature. It isevident that the`Delta_fG^(@)`curvefor theformationFeO `(or Fe_2O_3` not shownin thediagram )lies above the ` Delta _fG^(@)`curveforthe formation of`Al_2O_3`. Therefore, Al canreduce` FeOor Fe_ 2 O_ 3 ` to `2Al+2FeOoverset ( Delta ) to Al_2O_3+3Fe or "" 2 Al+ Fe_2O_3 overset (Delta ) to Al_2O_3 +2 Fe` Febut thereverseis not TRUE, i.e., Fecannotreduce `Al_2 O_3 `to` Al` ` ""2 Fe+Al_2 O_3 toFe_2O_3 +2Al ` Above 1073 K, theC, CO curvelies below Fe, FeO curve,therefore, above 1073, C can reducesFeO toFe. ` FeO+C overset ( gt 1073K) toFe+CO` In contrast, below 1073 K, the CO, `CO_2 `cuve lies below Fe, FeO curve, therefore,below 1073 K, CO canreduce FeOto Fe. ` "" FeO+COoverset ( lt 1073 K ) toFe+ CO _ 2`