Question

Which of the following reactions takes place at anode? (a) Reduction (b) Oxidation (c) Decomposition (d) Dissolution

Short answer

(b) Oxidation

Step-by-step solution

Understand Electrochemical Cell Processes

Within an electrochemical cell, the anode is the electrode where oxidation (loss of electrons) occurs. This is a fundamental principle of electrochemistry.

Identify the Reaction at the Anode

Since the anode is where oxidation occurs, we look for the process that involves a substance losing electrons. Among the provided options, oxidation is the type of reaction that involves the loss of electrons.

Eliminate Incorrect Options

Reduction involves gain of electrons and takes place at the cathode, not the anode. Decomposition is a type of reaction that may involve both reduction and oxidation but is not specific to the anode. Dissolution is simply the process of a solute dissolving in a solvent and is not specific to electrode reactions.

Select the Correct Option

From the given options, (b) Oxidation is the correct answer since it is the process that occurs at the anode in an electrochemical cell.

Key concepts

Oxidation at Anode

When studying electrochemical cells, it's crucial to understand the role of the anode. The anode is one half of the two electrodes in an electrochemical cell, with the other being the cathode.

In an electrochemical cell, the anode is characterized by the occurrence of oxidation reactions. These reactions involve the loss of electrons from a species. For instance, if you have a metal atom M, the oxidation reaction at the anode can be represented as follows: \( M \rightarrow M^{n+} + ne^{-} \). Here, \(n\) electrons (\(e^{-}\)) are lost by the metal atom, creating a positively charged ion \(M^{n+}\).

Understanding the concept of oxidation at the anode is fundamental in various applications of electrochemistry, such as batteries, where the anode releases electrons to generate electric current. It's also crucial when considering corrosion processes, where the metal is oxidized at the anode.

Electrochemistry Principles

Electrochemistry is the branch of chemistry that deals with the relationship between electricity and chemical reactions. A couple of fundamental principles underline this scientific field. First, it involves the study of both chemical changes that produce electrical energy and the use of electrical energy to bring about chemical transformations.

Electrochemical cells are the cornerstone of electrochemistry. They are systems that convert chemical energy into electrical energy or vice versa. The two key processes occurring in these cells are oxidation, which happens at the anode, and reduction, which occurs at the cathode.

Electrochemistry is governed by principles such as the flow of electrons from the anode to the cathode within an external circuit, the movement of ions within an electrolyte to maintain charge neutrality, and the concept of electrode potential, which determines the tendency of a species to be oxidized or reduced. This field is not only responsible for our understanding and development of batteries but also for electroplating, electrolysis, and sensing devices.

Reduction and Oxidation Processes

Reduction and oxidation, commonly known as redox processes, are chemical reactions involving the transfer of electrons between two substances. They always occur simultaneously in a pair, because if one species loses electrons (oxidation), another must gain them (reduction).

An easy way to remember this is by the mnemonic 'OIL RIG' - Oxidation Is Loss, Reduction Is Gain of electrons. The substance that donates electrons is known as the reducing agent, and the substance that accepts electrons is the oxidizing agent.

For example, in the reaction \(Cu^{2+} + Zn \rightarrow Cu + Zn^{2+}\), zinc (Zn) loses two electrons and is oxidized, while copper ions (\(Cu^{2+}\)) gain those electrons and are reduced. The overall redox process is essential in various applications, from energy storage in batteries to metabolic reactions in living organisms where molecules like glucose are oxidized to produce energy.