Identify redox reactions as reactions involving gain and loss of electrons

🔬 Redox Reactions – Gain and Loss of Electrons

What is a Redox Reaction?

Redox (short for reduction‑oxidation) is a chemical reaction where electrons are transferred between atoms. Think of it as a game of give‑and‑take – one atom gives electrons (gets oxidised) and another receives them (gets reduced). ⚡️

Key Features to Spot a Redox Reaction

• Atoms change their oxidation numbers.
• There is a clear electron transfer.
• Both an oxidation and a reduction half‑reaction can be written.

How to Identify Oxidation and Reduction

1. Assign oxidation numbers to every element.
2. Find which atoms change their numbers.
3. Mark the electron transfer: loss = oxidation, gain = reduction.

Example 1 – Iron Oxidation

$$\ce{Fe + \frac{1}{2}O2 -> FeO}$$

Oxidation numbers: Fe 0 → +2 (loses 2 e⁻), O 0 → –2 (gains 2 e⁻). 🔋

Example 2 – Zinc and Copper

$$\ce{Zn + Cu^{2+} -> Zn^{2+} + Cu}$$

Oxidation: Zn 0 → +2 (loses 2 e⁻). Reduction: Cu²⁺ → Cu 0 (gains 2 e⁻).

Quick Practice

1. Is the following a redox reaction? $$\ce{2H2 + O2 -> 2H2O}$$
2. Write the oxidation and reduction half‑reactions for $$\ce{Fe + S -> FeS}$$