Question

(a) What is meant by the term reduction? (b) On which side of a reduction half-reaction do the electrons appear? (c) What is meant by the term reductant? (d) What is meant by the term reducing agent?

Short answer

(a) Reduction is a process in which a molecule, atom, or ion gains electrons occurring in redox reactions. (b) In reduction half-reactions, electrons appear on the left side of the equation. (c) A reductant is a substance in a redox reaction that reduces another substance by providing it with electrons. (d) A reducing agent is a substance that reduces another substance by donating electrons during a redox reaction and becomes oxidized in the process.

Step-by-step solution

(a) Define reduction

In chemistry, reduction is a process in which a molecule, atom, or ion gains electrons. Reduction is a half-reaction that happens at the same time as the oxidation half-reaction, as part of redox (reduction-oxidation) reactions. In redox reactions, the substance that gains electrons gets reduced while the substance that loses electrons gets oxidized.

(b) Where do electrons appear in reduction half-reactions

In reduction half-reactions, the electrons appear on the left side of the equation, indicating that they are gained by the molecule, atom, or ion. For example, in the reduction half-reaction: \(\ce{Cu^{2+}} + 2e^- \rightarrow \ce{Cu}\), the electrons are on the left side, showing that the copper ion gains two electrons to become a neutral copper atom.

(c) Define reductant

A reductant, also known as a reducing agent, is a substance in a redox reaction that reduces another substance by providing it with electrons. In other words, the reductant becomes oxidized, losing electrons and causing the other substance to become reduced by gaining those electrons.

(d) Define reducing agent

A reducing agent, or reductant, is a substance that reduces another substance by donating electrons during a redox reaction. The reducing agent itself becomes oxidized in the process, meaning it loses electrons while the other substance gains electrons and is reduced. Reducing agents have the ability to transfer electrons from themselves to another substance, facilitating the reduction process.