Question

In each of the following instances, tell whether the substance gains electrons or loses electrons in a redox reaction: (a) An oxidizing agent (b) A reducing agent (c) A substance undergoing oxidation (d) A substance undergoing reduction

Short answer

(a) Gains electrons, (b) Loses electrons, (c) Loses electrons, (d) Gains electrons.

Step-by-step solution

Understand Oxidizing Agent

An oxidizing agent is a substance that gains electrons from another substance in a redox reaction. This means the oxidizing agent is reduced.

Understand Reducing Agent

A reducing agent is a substance that loses electrons to another substance in a redox reaction. This means the reducing agent is oxidized.

Substance Undergoing Oxidation

A substance undergoing oxidation loses electrons during the reaction.

Substance Undergoing Reduction

A substance undergoing reduction gains electrons during the reaction.

Key concepts

oxidizing agent

An oxidizing agent is essential in redox reactions. It takes electrons from another substance during the process. This means that the oxidizing agent itself undergoes a reduction.
When an oxidizing agent gains electrons, its charge becomes more negative or less positive. This is because electrons have a negative charge and adding them makes the atom or molecule more negative.

• An example of an oxidizing agent is oxygen, which commonly takes electrons from substances and is, therefore, reduced in many reactions.
• Another example is chlorine. When it gains electrons, it is reduced to chloride ions (Cl^-).

Knowing what an oxidizing agent does helps in understanding how substances interact during chemical reactions.

reducing agent

A reducing agent, also known as a reductant, plays the opposite role to an oxidizing agent in redox reactions. It gives up electrons to another substance, allowing the other substance to be reduced.
As a result of losing electrons, the reducing agent is oxidized. Its charge becomes more positive or less negative because it has fewer electrons, which have a negative charge.

• An example of a reducing agent is hydrogen. In many reactions, it donates its electrons to other substances and becomes oxidized.
• Metals, such as sodium, often serve as reducing agents because they easily lose electrons, forming positive ions.

Understanding reducing agents is crucial because it lets us predict how certain chemical reactions will proceed.

oxidation

Oxidation refers to the process where a substance loses electrons in a chemical reaction. This is a key component of redox reactions, where one species' loss of electrons leads to another's gain.
When a substance undergoes oxidation, it generally becomes more positively charged because electrons, which are negatively charged, are removed. This increase in positive charge reflects the loss of negatively charged electrons.

• A classic example is when iron is exposed to oxygen, forming rust. Here, iron loses electrons and oxidizes to form iron oxide.
• Additionally, oxidation can occur when an element gains oxygen, aligning with the historical definition of oxidation being about oxygen addition.

Recognizing when oxidation happens helps chemists control and utilize these reactions effectively.

reduction

Reduction, in contrast to oxidation, involves a substance gaining electrons. This gain leads to a decrease in the substance's oxidation state, often making it less positively charged.
Substances undergoing reduction acquire negatively charged electrons, leading to a more negative or less positive state. This is essential to redox reactions because reduction is the simultaneous gain of the electrons that another substance loses.

• For instance, when chlorine gas gains an electron, it is reduced to chloride ions. This process is fundamental in many types of cells and batteries.
• Another common example is when copper ions in solution gain electrons and deposit as solid copper.

Understanding reduction allows us to anticipate how substances change in chemical reactions, which is vital across scientific fields.