Question

How does the method used for extracting a metal from its ore depend on the metal's position in the reactivity series? Explain with examples.

Answer 1

Reactivity series depicts the reactivities of metals in decreasing order. It is very helpful in the extraction of metals. The extraction of metals depends on their reactivities.

For extraction purpose, metals in the reactivity series are ordered under three sections:
1. Highly reactive metals
2. Moderately reactive metals
3. Low reactive metals

Depending on the reactivities, different methods are applied for extracting metals from their ores.
Sodium, potassium, calcium, magnesium and aluminium are highly reactive metals and placed at the top of the reactivity series. These metals are extracted by electrolytic reduction of their molten chlorides or oxides because these metals are not reduced by other reducing agents like coke, carbon monoxide etc.

Moderately reactive metals like zinc, iron, lead and copper are placed at the middle of the reactivity series. They are reduced by carbon because carbon is more reactive than these metals and can reduce their metal oxides to metal easily. However, manganese is more reactive than zinc (above zinc in reactivity series); therefore, it cannot be reduced by carbon. It is reduced by a more reactive reducing agent aluminium. Aluminium reduces manganese dioxide to manganese on heating.

Low reactive metals like copper and mercury are placed at the bottom of the reactivity series and are extracted by heating their ores alone. We should note that ores of copper can be extracted by both $-$ reduction with carbon (copper (I) oxide) and heating alone (copper (I) sulphide).

Refer to the following diagram for quick glance of extraction of metals based on their reactivities: