Question

Electrolytic reduction process is used for the extraction of:
A. Alkali metals
B. Alkaline earth metals
C. Aluminium
D. All of these

Answer 1

Hint: There are many methods that are used for extracting the metals from their ores which include reduction of metal oxides with carbon or electrolytic reduction of the molten metal chlorides, oxides and hydroxides.

Complete step by step solution:
The type of extraction method to be used for the extraction of the metals from their ores depends upon its position in the reactivity series. Metals that lie below the carbon in the reactivity series can be extracted from their respective oxides by heating them with carbon. In this reaction, carbon gets oxidised to carbon dioxide while the metal oxide gets reduced to its respective metal. Such metals include Zinc, Iron, lead, tin and Copper.

But for the metals that lie above carbon in the reactivity series, their respective oxides cannot be reduced by heating it with carbon dioxide. These metals include sodium, potassium, calcium, magnesium and aluminium. For extracting these metals, electrolytic reduction of their respective molten chlorides, oxides or hydroxides is performed. Let us explain the electrolytic reduction method with the help of an example. Sodium is extracted by electrolytic reduction of molten sodium chloride. When the current is passed through fused sodium chloride, sodium ion is reduced at the cathode while chloride ions are oxidised at the anode. The chemical reactions are given below:

\[ \begin{matrix} At\quad anode: \\ At\quad cathode: \end{matrix}\begin{matrix} 2{ Cl }^{ - }+2{ e }^{ - }\longrightarrow { Cl }_{ 2 }(g) \\ 2N{ a }^{ + }\longrightarrow 2Na(s)+2{ e }^{ - } \end{matrix}\]

So, highly reactive metals such as alkali metals, alkaline earth metals and aluminium are extracted using electrolytic reduction.
So, the correct answer is (d) All of these.

Note: In the reactivity series, metals are arranged from the most reactive to the least reactive. This series is based upon the reactivity of different metals and non-metals which has been made after carefully observing their reactions with water, acids and other metal compounds.