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 chemical process in a redox reaction where a molecule or atom gains electrons from another species, decreasing its oxidation state. (b) In a reduction half-reaction, electrons appear on the left side or reactant side, e.g., \( Cu^{2+}(aq) + 2e^- \rightarrow Cu(s)\). (c) A reductant or reducing agent is a chemical species that donates electrons to another species in a redox reaction, leading to the reduction of the other species and the oxidation of the reductant. (d) A reducing agent is the same as a reductant and donates electrons in a redox reaction, causing the reduction of another species and its own oxidation.

Step-by-step solution

a) Definition of Reduction

Reduction is a chemical process that occurs in a redox (reduction-oxidation) reaction, where a molecule or atom gains electrons from another species. In other words, the reducing species donates electrons and thus reduces the other species. Reduction can be identified by observing a decrease in oxidation state.\

b) Side of a Reduction Half-Reaction with Electrons

In a reduction half-reaction, the electrons always appear on the left side or reactant side. An example of a half-reaction undergoing reduction is: \[ Cu^{2+}(aq) + 2e^- \rightarrow Cu(s) \] In this example, copper ions (Cu^{2+}) gain 2 electrons and turn into pure copper metal (Cu).

c) Definition of Reductant

A reductant, also referred to as a reducing agent, is a chemical species that donates electrons to another species in a redox reaction. This process leads to the reduction of the other species and the oxidation of the reductant.

d) Definition of Reducing Agent

A reducing agent is the same as a reductant—it is the chemical species that donates electrons to another species during a redox (reduction-oxidation) reaction. The reducing agent causes the reduction of another species by losing electrons itself, which leads to its oxidation.