Which term best fits the definition: a molecule that causes electron loss or removes electrons from a substrate?

• A. Oxidizing agent
• B. Reducing agent
• C. Catalyst
• D. Base

Answer: (A)

In redox chemistry, the person who pulls electrons away from another molecule is the oxidizing agent. It causes oxidation of the substrate by accepting electrons, so the substrate loses electrons while the oxidizing agent itself becomes reduced. The reducing agent, by contrast, donates electrons and causes oxidation in the other molecule. A catalyst merely speeds up the reaction without being consumed, and a base is about accepting protons, not electrons. So the term that fits “a molecule that causes electron loss or removes electrons from a substrate” is the oxidizing agent.