Question

Indicate whether each of the following statements is true or false: (a) If something is oxidized, it is formally losing electrons. (b) For the reaction \(\mathrm{Fe}^{3+}(a q)+\mathrm{Co}^{2+}(a q) \longrightarrow \mathrm{Fe}^{2+}(a q)+\) \(\mathrm{Co}^{3+}(a q), \mathrm{Fe}^{3+}(a q)\) is the reducing agent and \(\mathrm{Co}^{2+}(a q)\) is the oxidizing agent. (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.

Short answer

(a) True: In oxidation, a species loses electrons and its oxidation state increases. (b) True: In this reaction, $\mathrm{Fe}^{3+}(a q)$ is the reducing agent and $\mathrm{Co}^{2+}(a q)$ is the oxidizing agent. (c) True: If no changes in oxidation states occur, the reaction is not a redox reaction.

Step-by-step solution

Redox Reactions: Oxidation and Reduction

A redox reaction is a type of chemical reaction where the oxidation states of atoms change. In a redox reaction, one species undergoes oxidation, while the other undergoes reduction. Oxidation and reduction can be defined as follows: - Oxidation: The process in which a species loses electrons and its oxidation state increases. - Reduction: The process in which a species gains electrons and its oxidation state decreases. A redox reaction involves a transfer of electrons between two species.

Oxidizing Agents and Reducing Agents

The species that gains electrons is the oxidizing agent, and the species that loses electrons is the reducing agent. The oxidizing agent causes another species to be oxidized and itself undergoes reduction. The reducing agent causes another species to be reduced and itself undergoes oxidation. Now, let's determine whether the given statements are true or false.

Statement (a)

If something is oxidized, it is formally losing electrons. This statement is true. When a species is undergoing oxidation, it is losing electrons and its oxidation state increases.

Statement (b)

For the reaction $\mathrm{Fe}^{3+}(a q)+\mathrm{Co}^{2+}(a q) \longrightarrow \mathrm{Fe}^{2+}(a q)+\( \)\mathrm{Co}^{3+}(a q), \mathrm{Fe}^{3+}(a q)\( is the reducing agent and \)\mathrm{Co}^{2+}(a q)$ is the oxidizing agent. In this reaction, \(\mathrm{Fe}^{3+}(a q)\) is reduced to \(\mathrm{Fe}^{2+}(a q)\) because its oxidation state decreases from +3 to +2. At the same time, \(\mathrm{Co}^{2+}(a q)\) is oxidized to \(\mathrm{Co}^{3+}(a q)\), as its oxidation state increases from +2 to +3. Therefore, \(\mathrm{Fe}^{3+}(a q)\) is the reducing agent because it undergoes reduction, and \(\mathrm{Co}^{2+}(a q)\) is the oxidizing agent because it undergoes oxidation. This statement is also true.

Statement (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. This statement is true. A redox reaction requires a change in the oxidation states of the species involved. If there are no changes in the oxidation states during a reaction, it cannot be considered a redox reaction. To summarize, Statement (a) is True. Statement (b) is True. Statement (c) is True.

Key concepts

Oxidation

Oxidation is a process well understood in chemistry. It involves the loss of electrons by a molecule, atom, or ion. When an element undergoes oxidation, its oxidation state increases, signifying that it has lost electrons. This process is crucial in redox reactions, where the exchange of electrons occurs. For example, in the reaction between iron (\(\mathrm{Fe}^{3+}\)) and cobalt (\(\mathrm{Co}^{2+}\)), when \(\mathrm{Co}^{2+}\) loses an electron, it is said to be oxidized, forming \(\mathrm{Co}^{3+}\).

• Oxidation involves a gain in the positive charge.
• It is one-half of what makes a redox reaction complete.

Understanding oxidation is key to mastering the broader concept of redox reactions. Remember, whenever oxidation occurs, there must be a corresponding reduction elsewhere.

Reduction

Reduction is the counterpart to oxidation. It involves the gain of electrons by a molecule, atom, or ion. When an element is reduced, its oxidation state decreases, indicating an electron gain. In the context of redox reactions, reduction is a vital process, complementing oxidation. Going back to our example, the transition of \(\mathrm{Fe}^{3+}\) to \(\mathrm{Fe}^{2+}\) is a reduction, as the iron ion gains an electron.

• Reduction results in a decrease in oxidation state.
• It signifies an increase in negative charge or a decrease in positive charge.

In redox chemistry, both oxidation and reduction must occur simultaneously. This dual process ensures charge balance in reactions.

Oxidizing Agent

The oxidizing agent in a redox reaction is a substance that accepts electrons from another. By accepting electrons, it itself gets reduced. This agent plays a critical role in driving the oxidation process of the reactant. In our given reaction, \(\mathrm{Co}^{2+}\) acts as the oxidizing agent.

• It causes oxidation of the other substance.
• Meanwhile, it undergoes reduction.

Without an oxidizing agent, the transfer of electrons in a redox reaction can't be accomplished. Recognizing the oxidizing agent is essential for predicting the flow of electrons and outcomes in chemical reactions.

Reducing Agent

The reducing agent holds the task of donating electrons in a redox reaction. By providing electrons to another species, the reducing agent undergoes oxidation. This agent is essentially the driver for the reduction process in redox reactions. In our examined reaction, \(\mathrm{Fe}^{3+}\) is the reducing agent since it gets oxidized to \(\mathrm{Fe}^{2+}\).

• It donates electrons to another species.
• It causes the reduction of its reactant partner.

Identifying the reducing agent can help one understand which component of a reaction is losing electrons, making it key to understanding chemical interactions.

Oxidation State

The oxidation state is a concept used to keep track of electron transfers in chemical reactions. It allows chemists to keep a tab on how electrons are distributed among the atoms in a molecule. Essentially, the oxidation state provides a hypothetical charge of an atom within a compound if the electrons were transferred completely.

• A higher oxidation state means more lost electrons.
• A lower oxidation state indicates electron gain.

By examining changes in oxidation states, one can determine which elements undergo oxidation or reduction in a redox reaction. It is crucial for understanding and predicting the electron exchange that occurs during chemical processes.