Question

What are the different reducing agents which are used to reduce the metal oxides? Describe how they work with different oxides of metal.

Short answer

Answer: Common reducing agents for reducing metal oxides include carbon (coke or coal), carbon monoxide, hydrogen, and reactive metals such as aluminum, magnesium, sodium, and calcium. These agents donate electrons to the metal oxides in a redox reaction, causing the metal to revert to its elemental form and the oxygen to be removed. Each reducing agent works with specific metal oxides; for example, carbon is used in the blast furnace process for iron oxide reduction, hydrogen can reduce copper oxide, and aluminum can reduce iron oxide in a thermite reaction known as the Goldschmidt process.

Step-by-step solution

1. Introduction to Reducing Agents

A reducing agent is a substance that donates electrons to another substance (reduced) in a redox chemical reaction, thus undergoing oxidation itself. In the context of reducing metal oxides, the reducing agents help to remove oxygen from the metal oxides, returning the metal to its elemental form.

2. Common Reducing Agents

There are several common reducing agents which can reduce metal oxides, including: a. Carbon - in the form of coke or coal b. Carbon monoxide - produced during the reduction process c. Hydrogen d. Metals - such as aluminum, magnesium, sodium, and calcium (used in thermite reactions)

3. Reducing Metal Oxides with Carbon

Carbon, in the form of coke or coal, is widely used to reduce metal oxides. This is particularly true for iron oxide (Fe2O3) in the blast furnace process. The reaction, known as smelting, heats the iron ore (iron oxide) with carbon at high temperatures. The carbon (C) reduces the iron oxide (Fe2O3) to form iron (Fe) and carbon dioxide (CO2). Fe2O3 + 3C -> 2Fe + 3CO2

4. Reducing Metal Oxides with Carbon Monoxide

Carbon monoxide is another reducing agent, usually produced along with carbon during the reduction process of metal oxides. For example, in the reduction of iron oxide (Fe2O3) in a blast furnace, carbon monoxide (CO) is one of the primary reducing agents: Fe2O3 + 3CO -> 2Fe + 3CO2

5. Reducing Metal Oxides with Hydrogen

Another method for reducing metal oxides involves reacting them with hydrogen (H2) at elevated temperatures to form water (H2O) and the reduced metal. One example of this type of reduction is the production of copper (Cu) from copper oxide (CuO) using hydrogen: CuO + H2 -> Cu + H2O

6. Reducing Metal Oxides with Metals

In some cases, more reactive metals can reduce metal oxides. For example, aluminum (Al) can reduce iron oxide (Fe2O3) in a thermite reaction known as the Goldschmidt process: Fe2O3 + 2Al -> Al2O3 + 2Fe Here, aluminum loses electrons and gets oxidized, while iron oxide gains electrons and gets reduced. The energy released in this highly exothermic reaction produces molten iron and aluminum oxide as the products.