Question

How is an oxidation-reduction reaction set up as a galvanic cell (battery)? How is the transfer of electrons between reducing agent and oxidizing agent made useful?

Short answer

An oxidation-reduction reaction is set up as a galvanic cell by creating two half-cells, each containing an electrode and electrolyte solution, connected by a salt bridge or porous membrane. The electrodes are made of the reducing and oxidizing agents, and the electrolyte solutions contain the ions of the redox reaction. These half-cells are then connected with an external wire, allowing for the transfer of electrons between the reducing and oxidizing agents, generating an electrical current. The transfer of electrons in a galvanic cell is useful, as it converts the chemical energy released in the redox reaction into electrical energy, powering devices or charging batteries.

Step-by-step solution

1. Understanding Oxidation-Reduction Reactions

Oxidation-reduction reactions involve the transfer of one or more electrons between species. One species (the reducing agent) loses electrons, and the other species (the oxidizing agent) gains electrons. The transfer of electrons results in changes in the oxidation states of the species involved in the reaction.

2. Introduction to Galvanic Cells

A galvanic cell, also known as a voltaic cell, is an electrochemical cell that produces an electrical current through a spontaneous redox reaction. It consists of two half-cells connected by a salt bridge or porous membrane. The half-cells contain a semi-solid electrode, which is either oxidized or reduced, and an electrolyte solution, which contains ions of the redox reaction.

3. Setting Up a Galvanic Cell

In order to set up an oxidation-reduction reaction as a galvanic cell, follow these steps: 1. Identify the reducing and oxidizing agents in the redox reaction. 2. Set up the two half-cells by placing the electrodes (usually metals) of the reducing and oxidizing agents into separate containers. 3. Fill the containers with an electrolyte solution that contains the ions of the redox reaction. 4. Connect the two half-cells with a salt bridge or porous membrane, which allows the flow of ions between the half-cells to maintain charge neutrality and complete the electrical circuit. 5. Connect the electrodes of the half-cells with a wire, allowing the flow of electrons from the reducing agent to the oxidizing agent.

4. Utilizing the Electron Transfer in a Galvanic Cell

The transfer of electrons between the reducing agent and oxidizing agent in a galvanic cell is made useful by converting the chemical energy released in the redox reaction into electrical energy. This electrical energy can be harnessed to power electrical devices or charge batteries. The flow of electrons through the external wire generates an electrical current, which can be used to do work. In summary, an oxidation-reduction reaction is set up as a galvanic cell by creating two half-cells that allow the transfer of electrons between the reducing and oxidizing agents through an external wire. The flow of electrons generates an electrical current, which can be used to power devices or store energy in batteries.

Key concepts

Oxidation-Reduction Reactions

Oxidation-reduction reactions, commonly known as redox reactions, are fundamental chemical processes where electrons are transferred between substances. They consist of two half-reactions: oxidation, where a substance loses electrons, and reduction, where a substance gains electrons. The substance that loses electrons is called the 'reducing agent' and the one that gains electrons is the 'oxidizing agent'.

Understanding redox reactions is crucial because they are involved in various chemical and biological processes. For example, in photosynthesis, plants use redox reactions to convert light energy into chemical energy. In the context of galvanic cells, these reactions are harnessed to produce electrical energy from chemical reactions.

Electrochemical Cells

Electrochemical cells, including galvanic cells, are devices that convert chemical energy into electrical energy through redox reactions. There are two primary types of electrochemical cells: galvanic cells, which generate electricity spontaneously, and electrolytic cells, which use external electricity to drive non-spontaneous chemical reactions.

In a galvanic cell, the redox reaction is set up in two separate half-cells, allowing for a controlled flow of electrons. The completion of the circuit through an external wire enables the transfer of electrons from the anode to the cathode, generating an electrical current. It's this current that can be used to power electronic devices or store energy in batteries.

Electrical Current in Chemistry

The flow of electrical current in chemical reactions is facilitated by the movement of electrons. In the context of redox reactions, as electrons are transferred from the reducing agent to the oxidizing agent, an electrical current is created. This current originates at the molecular level but can be amplified to power everyday electronic devices.

Additionally, the measure of this current is based on the number of electrons moving past a certain point per second, known as amperes (A). Factors such as the concentration of reactants, temperature, and cell voltage can affect the strength of the current produced in a galvanic cell.

Half-Cells in Galvanic Cells

Half-cells are the two separate compartments of a galvanic cell where oxidation and reduction half-reactions occur independently. Each half-cell contains an electrode submerged in an electrolyte solution of ions that participate in the redox reaction.

The two half-cells are connected via a salt bridge or porous membrane, which allows ions to flow and maintain electrical neutrality. Meanwhile, the electrodes are connected by an external wire. As the redox reaction proceeds, electrons flow from the reducing agent at the anode to the oxidizing agent at the cathode. The control over these isolated reactions in half-cells is essential for the efficient generation of electrical energy and the practical use of galvanic cells in everyday applications.