MCQ Detailed View

In metallurgy, a reducing agent is a substance that donates electrons to a metal compound, usually an oxide, and reduces it to the metallic state. The most commonly used reducing agent in smelting of metals is carbon, usually in the form of coke.

During smelting, metal oxides are heated with carbon at high temperatures. The carbon reacts with the oxygen in the metal oxide to form carbon monoxide (CO) or carbon dioxide (CO₂), leaving behind the pure metal. For example, in the extraction of iron from hematite (Fe₂O₃) in a blast furnace, the reactions are:

C + O₂ → CO₂
Fe₂O₃ + 3CO → 2Fe + 3CO₂

Carbon is preferred as a reducing agent because it is abundant, inexpensive, and effective at high temperatures. It is widely used in the extraction of metals such as iron, copper, zinc, and lead.

Other metals like zinc, aluminium, or copper are not commonly used as reducing agents in large-scale smelting:

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  Zinc (Zn) is usually reduced from its ore using carbon or by electrolysis.

  
  


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  Aluminium (Al) is highly reactive but used in the thermite process for special reductions, not general smelting.

  
  


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  Copper (Cu) is often obtained by roasting and smelting without acting as a reducing agent.

  
  

Understanding the role of carbon in smelting helps students learn about redox reactions, extraction techniques, and industrial metallurgy. The concept demonstrates how electron transfer and chemical reactivity are applied to obtain pure metals from their ores efficiently.