4.10
Certain processes that are vital to life, including photosynthesis, combustion, and corrosion, fall into the class of reactions called oxidation–reduction, or redox, reactions.
Redox reactions consist of two simultaneous processes: oxidation and reduction.
The term oxidation means an increase in oxidation number, which corresponds to the loss of electrons, while reduction means a decrease in oxidation number, which corresponds to the gain of electrons. To remember the role of electrons, use the acronym OIL RIG, which stands for: “oxidation is losing, reduction is gaining.”
Oxidation and reduction are complementary processes. In a redox reaction between two reactants, one reactant loses electrons and is oxidized, while the other reactant gains electrons and is reduced.
Consider the oxidation–reduction reaction between potassium — an alkali metal — and chlorine, a nonmetal.
The neutral potassium atom loses an electron to become a potassium ion. Potassium is oxidized, and its charge increases from zero in the neutral atom to one-plus in the cation.
The neutral chlorine atom gains an electron and becomes a chloride ion. Chlorine is reduced, and its charge decreases from zero in the neu
Earth’s atmosphere contains about 20% molecular oxygen, O2, a chemically reactive gas that plays an essential role in th…
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