Define oxidation as gain of oxygen and reduction as loss of oxygen

Chemical Reactions – Redox

What is Oxidation?

Oxidation is like giving a chemical a “bite” of oxygen. In a redox reaction, the substance that gains oxygen is said to be oxidised. Think of it as a superhero gaining power by absorbing oxygen.

What is Reduction?

Reduction is the opposite: the substance loses oxygen (or gains electrons). It’s like a superhero losing power, but gaining strength in a different way.

Simple Example: Iron Rusting

When iron reacts with oxygen and water, it forms iron(III) oxide:

  1. Iron (Fe) gains oxygen atoms.

  2. Water (H₂O) loses oxygen atoms (the hydrogen is oxidised).

Equation:

\$\text{Fe} + \frac{3}{2}\text{O}2 + \text{H}2\text{O} \rightarrow \text{Fe}2\text{O}3 \cdot \text{H}_2\text{O}\$

Oxidation Numbers – Quick Check

Use a table to see who is gaining and who is losing oxygen.

CompoundOxidation State of FeOxidation State of O
Fe0-2
Fe₂O₃+3-2

Quick Quiz

  • Which element is oxidised in the reaction between hydrogen and oxygen to form water? Answer: Hydrogen (gains oxygen)

  • Which element is reduced in the same reaction? Answer: Oxygen (loses oxygen)

Remember

In any redox reaction:

  • Oxidation = gain of oxygen (or gain of electrons).

  • Reduction = loss of oxygen (or gain of electrons).

Use the oxidation number table to check who is doing what. Good luck! 🚀