Chapter 16 · Oxidation and Reduction
16.2Oxidation and Reduction: Some Definitions
9 min · two checks
Predict
In a redox reaction, which process is oxidation?
The idea
- Define oxidation, reduction, and the two agents.
- Identify them in a simple metal displacement.
Oxidation is loss of electrons. Reduction is gain. They are simultaneous. The oxidizing agent is the substance that causes oxidation by taking electrons; it gets reduced. The reducing agent donates electrons and gets oxidized. In Zn + Cu²⁺ → Zn²⁺ + Cu, zinc is oxidized and is the reducing agent. Copper(II) ion is reduced and is the oxidizing agent.
Older definitions said oxidation was gaining oxygen or losing hydrogen, and those cases still fit, because the electron count moves the same way. The electron definition is the one that covers batteries and half-reactions. If you cannot see electrons in the equation, oxidation states in the next section will show where they went.
Keep these
- Oxidation: electron loss. Reduction: electron gain.
- The oxidizing agent is reduced. The reducing agent is oxidized.
- The two processes always occur together.