(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?

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Reduction is a chemical reaction that involves the gain of electrons by a molecule, atom, or ion. It is one half of a redox (reduction-oxidation) reaction, where the other half is oxidation, which involves the loss of electrons.

In a reduction half-reaction, electrons appear on the reactant side (left side) of the equation. This is because the species undergoing reduction is gaining electrons.

A reductant, also known as a reducing agent, is a substance that donates electrons to another species in a chemical reaction. By donating electrons, the reductant itself becomes oxidized.

The term 'reducing agent' is synonymous with 'reductant.' It refers to the substance that causes another substance to be reduced by donating electrons to it. In the process, the reducing agent is oxidized.

In summary, reduction involves gaining electrons, and the reducing agent is the species that provides these electrons, thus undergoing oxidation itself.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Reduction

Reduction is a chemical process involving the gain of electrons by a substance. It is one half of a redox (reduction-oxidation) reaction, where one species is reduced while another is oxidized. In this context, the oxidation state of the reduced species decreases, indicating a transformation that often leads to the formation of more stable compounds.

Electrons in Reduction Half-Reaction

In a reduction half-reaction, electrons are added to the reactant, appearing on the left side of the equation. This signifies that the species is gaining electrons, which is essential for understanding how reduction occurs in redox reactions. For example, in the reduction of copper ions to copper metal, electrons are shown as reactants.

Reducant and Reducing Agent

A reductant, or reducing agent, is a substance that donates electrons in a chemical reaction, causing another substance to be reduced. It undergoes oxidation itself in the process. Understanding the role of the reducing agent is crucial in redox chemistry, as it helps identify which species facilitates the reduction of another.

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Related Practice

Textbook Question

Magnesium, the element, is produced commercially by electrolysis from a molten salt (the 'electrolyte') using a cell similar to the one shown here. (b) Chlorine gas is evolved as voltage is applied in the cell. Knowing this, identify the electrolyte.

Textbook Question

Magnesium, the element, is produced commercially by electrolysis from a molten salt (the 'electrolyte') using a cell similar to the one shown here. (c) Recall that in an electrolytic cell the anode is given the + sign and the cathode is given the – sign, which is the opposite of what we see in batteries. What half-reaction occurs at the anode in this electrolytic cell?

Textbook Question

(b) On which side of an oxidation half-reaction do the electrons appear?

Textbook Question

Indicate whether each of the following statements is true or false: (a) If something is oxidized, it is formally losing electrons.

Textbook Question

Indicate whether each of the following statements is true or false: (c) If there are no changes in the oxidation state of the reactants or products of a particular reaction, that reaction is not a redox reaction.

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Textbook Question

Indicate whether each of the following statements is true or false: (c) An oxidizing agent is needed to convert CO into CO₂.