Answer to Question #74562 in Inorganic Chemistry for srikant behera

Question

Why suitable reducing agents are required for reduction of metal oxides? What are the
guidelines to choose a particular reducing agent?

Answer 1

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.