How It Works: Electron Transfer in Redox

⚙️ How It Works: Electron Transfer in Redox

In every redox reaction, electrons move from one species to another. The species that gives away electrons is called the reducing agent (it causes reduction in the other species). The species that accepts electrons is called the oxidising agent (it causes oxidation in the other species).

Consider the reaction between magnesium and oxygen: 2Mg + O₂ → 2MgO. Magnesium atoms each lose 2 electrons to become Mg²⁺ ions (oxidised). Oxygen molecules each gain 4 electrons to become two O²⁻ ions (reduced). Magnesium is the reducing agent (it causes the oxygen to be reduced). Oxygen is the oxidising agent (it causes the magnesium to be oxidised).

In the blast furnace, iron is extracted using carbon monoxide as the reducing agent: Fe₂O₃ + 3CO → 2Fe + 3CO₂. The iron ions in Fe₂O₃ are reduced (gain electrons, lose oxygen), and the carbon monoxide is oxidised (gains oxygen to form CO₂). The reducing agent here is CO.

A key point: Oxidation and reduction always occur together — you cannot have one without the other. The electrons lost by one species are exactly the electrons gained by another. This is why "redox" reactions are so named.