Concept Explanation: Reduction of Metal Oxides

Moderately reactive metals (such as Zinc, Iron, Nickel, Tin, Copper) have oxides that are not easily reduced. Their position in the reactivity series is below highly reactive metals (like Sodium, Calcium) but above less reactive metals. To extract these metals from their oxides, a suitable reducing agent is used, which can donate electrons to reduce the metal oxide to the metal.

Step 1: Understand the Reactivity Series

The reactivity series arranges metals in order of decreasing reactivity. A metal can reduce the oxide of another metal that is below it in the series. For example:

Aluminium (more reactive) can reduce iron oxide (less reactive):

Step 2: Evaluate the Reducing Agents

Consider each option:

• Calcium: Highly reactive, but expensive and not commonly used for moderate metals.
• Aluminium: Used in thermite process for specific metals (e.g., iron), but not universal.
• Sodium: Too reactive and expensive; may form alloys or be unsafe.
• Carbon (as coke or coal): Economical and effective; reduces oxides by forming CO/CO₂. Widely used for Zn, Fe, Sn, Cu, etc.

Step 3: Why Carbon is Preferred

Carbon is below these moderate metals in reactivity (except for Zn, which is similar, but still workable). It reduces oxides at high temperatures in blast furnaces or similar setups. For example, for tin oxide:

It is cheap, abundant, and efficient for large-scale extraction.

Final Answer

Carbon is the most suitable reducing agent for oxides of moderately reactive metals like Zinc, Iron, Nickel, Tin, Copper.

Related Topics

• Reactivity Series of Metals
• Extraction of Metals (Metallurgy)
• Redox Reactions
• Thermite Process (for aluminium reduction)

Important Formulae

General reduction with carbon: Metal Oxide + Carbon → Metal + Carbon Monoxide/Dioxide

Example for iron:

Thermite reaction (aluminium reduction):