Question

Carbon cannot reduce the oxides of sodium, magnesium, and aluminium of their respective metals. Why? Where are these metals placed in the reactivity series? How are these elements obtained from their ores? Take an example to explain the process of extraction along with chemical equations.

Answer 1

Yes, carbon cannot reduce the oxides of sodium, magnesium, and aluminium because the reactivity of these elements is more than carbon so carbon can not reduce these highly reactive elements.

$$\begin{gathered} {\mathrm{Na}}_2\mathrm{O}+\mathrm{C}\to \times \\ \mathrm{MgO}+\mathrm{C}\to \times \\ {\mathrm{Al}}_2{\mathrm{O}}_3+\mathrm{C}\to \times \end{gathered}$$

Reactivity depends upon the oxidation potential of the elements which have been recorded with respect to Hydrogen.

The reactivity series is as follows:

Potassium(K)

Sodium(Na)

Calcium(Ca)

Magnesium(Mg)

Aluminium (Al)

Carbon(C)

Zinc(Zn)

Iron(Fe)

Tin(Sn)

Lead(Pb)

Hydrogen(H)

Copper(Cu)

Silver(Ag)

Gold(Au)

This is the decreasing order of reactivity of different elements so the element which is present below the other element can not displace it from its salt solution but an element present above can displace the lower element from its salt solution.

As we can observe carbon is below all these reactive elements like sodium, magnesium, and aluminium which means the carbon is not that much reactivity as these elements have that's why carbon can not reduce them from their solution.

Extraction of highly reactive metals: The highly reactive metals are extracted by using an electrolytic reduction process in which an electric current passed in a battery where these elements are extracted in their pure forms.