Question

Use this unbalanced redox equation $$ \mathrm{KMnO}_{4}+\mathrm{HCl} \longrightarrow \mathrm{KCl}+\mathrm{MnCl}_{2}+\mathrm{H}_{2}+\mathrm{Cl}_{2} $$ to indicate (a) the oxidizing agent (b) the reducing agent (c) the number of electrons that are transferred per mole of oxid izing agcnt

Short answer

Oxidizing agent: KMnO\(_4\); Reducing agent: HCl; Electrons transferred: 10 per mole of KMnO\(_4\).

Step-by-step solution

Identify the oxidation states of elements

Assign oxidation states to each element in the equation \( \text{KMnO}_4 + \text{HCl} \rightarrow \text{KCl} + \text{MnCl}_2 + \text{H}_2 + \text{Cl}_2 \). Manganese (Mn) in permanganate (KMnO\(_4\)) has an oxidation state of +7, while in MnCl\(_2\), it is +2. Chlorine (Cl) in HCl has an oxidation state of -1, while in Cl\(_2\), it is 0.

Determine the changes in oxidation states

Note the changes in oxidation states for manganese and chlorine. Manganese changes from +7 in KMnO\(_4\) to +2 in MnCl\(_2\), indicating it is reduced. Chlorine changes from -1 in HCl to 0 in Cl\(_2\), indicating it is oxidized.

Identify the oxidizing and reducing agents

The substance that is reduced (KMnO\(_4\)) is the oxidizing agent, and the one that is oxidized (HCl) is the reducing agent.

Calculate the number of electrons transferred

Determine the number of electrons transferred for the changes in oxidation states. Manganese changes from +7 to +2, a gain of 5 electrons per Mn atom. Chlorine changes from -1 to 0, a loss of 1 electron per Cl atom. Since there are 2 chlorine atoms in one Cl\(_2\) molecule, the total number of electrons lost by chlorine is 2. The reduction and oxidation must balance, so the number of electrons transferred is the least common multiple of 5 (Mn) and 2 (Cl), which is 10.

Key concepts

oxidizing agent

An oxidizing agent is a substance that gains electrons during a chemical reaction. It helps another substance to lose electrons. Therefore, the oxidizing agent itself gets reduced in the process.

In the provided redox equation, \textbf{KMnO}\(_4\) is the oxidizing agent. Let's break this down:

- \textbf{KMnO}\(_4\) contains manganese with a +7 oxidation state.
- Manganese in \textbf{KMnO}\(_4\) gets reduced to a +2 oxidation state in \textbf{MnCl}\(_2\).
- Hence, \textbf{KMnO}\(_4\) accepts 5 electrons per manganese atom, making it reduced and acting as the oxidizing agent.

Oxidizing agents are crucial in various chemical processes, including combustion, respiration, and industrial applications. When using oxidizing agents, ensure to follow safety guidelines as they can be reactive and sometimes hazardous.

reducing agent

A reducing agent is a substance that loses electrons in a chemical reaction. It donates electrons to another substance, thus causing that substance to be reduced. Consequently, the reducing agent itself becomes oxidized.

In our redox reaction, \textbf{HCl} serves as the reducing agent. Here's why:

- \textbf{HCl} contains chlorine with a -1 oxidation state.
- Chlorine in \textbf{HCl} is oxidized to a 0 oxidation state in \textbf{Cl}\(_2\).
- This indicates that \textbf{HCl} loses electrons (1 electron per chlorine atom, but since there are 2 chlorine atoms involved in forming \textbf{Cl}\(_2\), the total is 2 electrons lost).

Reducing agents are essential in processes such as metal extraction and organic synthesis. Understanding the role of reducing agents can help in better grasping chemical reactions and reactivity trends.

electron transfer

Electron transfer is a fundamental concept in redox reactions. It involves the movement of electrons from the reducing agent to the oxidizing agent.

Let's recap the electron transfer in the given redox reaction:

- Manganese in \textbf{KMnO}\(_4\) gains 5 electrons as it reduces from an oxidation state of +7 to +2.
- Chlorine in \textbf{HCl} loses 1 electron per atom (2 electrons total since \textbf{Cl}\(_2\) forms) as it oxidizes from an oxidation state of -1 to 0.
- To balance the electron transfer, we calculate the least common multiple of 5 (electrons gained by Mn) and 2 (electrons lost by Cl), which is 10.

Thus, 10 electrons are transferred per mole of oxidizing agent (\textbf{KMnO}\(_4\)). This balance ensures that the number of electrons lost equals the number of electrons gained, making the process consistent with the law of conservation of mass and charge.