InterviewSolution
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InterviewSolution
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In what condition extraction of `Mg` is possible by `MgO` using carbon reduction method. |
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Answer» According to Ellinghan diagram reduction of metal oxide with carbon will occur when the accompaying `DeltaG` is negative. Such reduction become feasible at very high temperature. `MgO` can only be reduced by carbon at the temperature approximate `2000^(@)C`. `Mg` form by heating `MgO` and `C` at `2000^(@)C`, at this temperature or above `C` reduces `MgO`. The gaseous mixture of `Mg` and `CO` was then cooled very repidly to deposit the metal. This quenching or shockooling was necessary as the reaction is reversible, and if cooled slowely the reaction will come to equilibrium further to teh left and we get `Mg`. `Mg + C hArr Mg +CO` Limitations of Ellinghan Diagram: (a) The graph simply indicates whether a reaction is possible or not i.e. the tendency of reduction with a reducing agent is indicated. This is so because it is based only on the thermodynamic concepts. It doe not say about the kinetics of teh reduction process (Cannot answer questions like how fast it could be?) (b) The interpretation of `DeltaG^(Theta)` is based on `K(DeltaG^(Theta) =- RT` InK). Thus it is persumed that the reactants of products are in equilibrium. `M_(x)O +A_(red) 1 xM +AO_(OX)` |
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