​What is Oxidation-Reduction?

​A chemical reaction in which electrons are transferred from one atom or ion to another is called an oxidation-reduction reaction, commonly known as a redox reaction.

A common oxidation reaction occurs when iron metal loses electrons to oxygen. Metals are painted to stop this corrosive reaction.

​Oxidation

​Oxidation is the loss of electrons by the atoms or ions of a substance. The element that loses the electrons is oxidized and becomes more positively charged; that is, its oxidation number increases.

→ [Zn]²⁺ + 2e^- (loss of electrons)

​Reduction

​Reduction is the gain of electrons by the atoms or ions of a substance. The element that acquires the electrons becomes more negatively charged.

+ 2e^- → (gain of electrons)

​Combining Half-Reactions

​The balanced overall equation for the reaction can be written as shown below.

2Zn⁰ + O₂⁰ → 2Zn²⁺ + 2O^2-

​Each atom of zinc atom donates two electrons to each oxygen atom.

Each zinc atom loses electrons and is oxidized.

Each oxygen atom gains and is therefore reduced.

​Identifying a Redox Reaction

​Redox reactions always involve the the exchange of electrons and many of them involve ionic compounds. Oxygen is not required for an oxidation-reduction reaction.

2Na_(s) + Cl_2(g) → 2NaCl_(s)

​Identifying a Redox Reaction

​An oxidation-reduction does not require oxygen to be present. Oxidation-reduction reaction involve the exchange of electrons and involve ionic compounds.

​Oxidizing and Reducing Agents

• ​ An oxidizing agent is the substance that gains electrons in a redox reaction.

• A reducing agent is the substance that loses electrons in a redox reaction.