Why suitable reducing agents are required for reduction of metal oxides? What are the
guidelines to choose a particular reducing agent?
Answer: one way to produce pure metals is to recover them from oxides. However, each metal has its own electrode and chemical potentials, which, in principle, are related to each other. In this connection and, on the basis of this, a suitable reducing agent is needed to produce the metal from its oxide. Recommendations for choosing a specific reductant are some patterns that are identified by experience. In particular, there is one main recommendation: the reductant must be selected in such a way that the potential in the oxidation-reduction system is positive. So, for example, consider the reduction of aluminum from its oxide. In aluminum, the standard electrode potential is -1.663 V in order for the reaction's EMF to be positive, it is necessary to select a reductant whose potential would be more negative than the aluminum potential, since the system's EMF is the difference between the potentials of the cathode and the anode. This reducing agent can be magnesium, whose potential is -2.363 V. In this case, the EMF will be -1.663 + 2.363 = 0.7 V.