Which term describes the reactant in a redox reaction that gains electrons and becomes reduced?

• A. Oxidizing Agent
• B. Reducing Agent
• C. Half-reactions
• D. Galvanic Cell

Answer: (A)

In a redox reaction, electrons move from one species to another. Oxidation is the loss of electrons, while reduction is the gain of electrons. The species that gains electrons is the one that gets reduced, and the substance that brings about this reduction by accepting electrons is called the oxidizing agent. That’s why the reactant that gains electrons and becomes reduced is described as the oxidizing agent—it causes oxidation in the other species by taking electrons from it and is itself reduced in the process. For example, in acidic permanganate reactions, MnO4− gains electrons to become Mn2+, so MnO4− acts as the oxidizing agent. The reducing agent, by contrast, donates electrons and is oxidized.