What is Galvanic and Electrolytic Cell: Introduction
To differentiate between galvanic and electrolytic cells: Galvanic and electrolytic cells are key components in the field of electrochemistry. Galvanic cells convert chemical energy into electrical energy through spontaneous redox reactions, utilizing two half-cells containing electrodes immersed in an electrolyte solution. In contrast, electrolytic cells employ an external power source to drive non-spontaneous redox reactions. These cells play vital roles in various applications such as batteries, fuel cells, and industrial processes, providing a deeper understanding of electrochemical phenomena and energy conversion. Let’s understand them further in depth.
Last updated date: 25th Sep 2023
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What is Galvanic Cell?
A galvanic cell, also known as a voltaic cell, is an electrochemical device that converts chemical energy into electrical energy through spontaneous redox reactions. It consists of two half-cells, each containing an electrode immersed in an electrolyte solution. The half-reaction occurring at the anode involves oxidation, where electrons are released, while at the cathode, reduction takes place, resulting in the gain of electrons. The flow of electrons through an external circuit generates an electric current, allowing for the extraction of electrical energy. Galvanic cells play a significant role in various practical applications, including batteries, fuel cells, and power sources, and understanding their operation is crucial in the study of electrochemistry and energy conversion. The characteristics of galvanic cells are:
Spontaneous Reaction: Galvanic cells operate through spontaneous redox reactions, meaning that chemical reactions occur naturally without the need for an external power source.
Energy Conversion: These cells convert chemical energy into electrical energy. The redox reactions at the anode and cathode generate a flow of electrons through an external circuit, producing an electric current that can be utilized for various applications.
Half-Cell Configuration: Galvanic cells consist of two half-cells, each with an electrode and an electrolyte solution. The anode half-cell houses the oxidation reaction, while the cathode half-cell facilitates the reduction reaction.
Electron Flow: The oxidation half-reaction at the anode releases electrons, which then flow through an external circuit to the cathode, where the reduction half-reaction occurs. This electron flow creates an electric current.
Salt Bridge or Porous Barrier: To maintain charge neutrality and prevent the buildup of excess positive or negative charges, galvanic cells employ a salt bridge or a porous barrier. It allows the migration of ions between the half-cells, balancing the charge and completing the circuit.
Cell Potential: Galvanic cells have a measurable potential difference, known as the cell potential or electromotive force (EMF). It represents the driving force behind the flow of electrons and can be measured in volts.
What is Electrolytic Cell?
An electrolytic cell is an electrochemical device that uses an external power source to drive a non-spontaneous redox reaction. Unlike galvanic cells, which produce electrical energy, electrolytic cells consume electrical energy to induce a chemical reaction. The cell consists of an electrolyte solution and two electrodes: the anode, which is connected to the positive terminal of the power source, and the cathode, linked to the negative terminal. When the power source is turned on, cations from the electrolyte are attracted to the cathode, where they undergo reduction, while anions migrate to the anode and undergo oxidation. Electrolytic cells are widely used in applications such as electroplating, metal extraction, and electrolysis processes. They play a crucial role in industry and provide insights into the principles of electrochemistry and energy transformations. The characteristics of electrolytic cells are:
Non-spontaneous Reaction: Unlike galvanic cells, electrolytic cells drive non-spontaneous redox reactions. They require an external power source to force the desired chemical reaction to occur.
Electrical Energy Consumption: Electrolytic cells consume electrical energy from the external power source to facilitate the electrolysis process.
Electrolyte Solution: Electrolytic cells contain an electrolyte solution, typically a liquid or molten salt that conducts electricity. The electrolyte provides ions necessary for the chemical reaction to take place.
External Power Source: An electrolytic cell is connected to an external power source, such as a battery or direct current (DC) power supply. The positive terminal of the power source is connected to the anode, while the negative terminal is connected to the cathode.
Electrode Reactions: At the cathode, reduction occurs as electrons are gained, while at the anode, oxidation takes place as electrons are released.
Chemical Transformations: Electrolytic cells are used for various chemical transformations, including electroplating, metal refining, production of chemical compounds, and electrolysis of water to generate hydrogen and oxygen gases.
Differentiate between Galvanic and Electrolytic Cell
Spontaneous redox reaction
Non-spontaneous redox reaction
Converts chemical energy into electrical energy
Consumes electrical energy
No external power source required
Requires an external power source (battery or DC)
Electrons flow from anode to cathode
Electrons flow from cathode to anode
Has a measurable cell potential (EMF)
Does not have a cell potential
Used as batteries, fuel cells, power sources, etc.
Used in electroplating, metal extraction, electrolysis, etc.
This table provides a concise overview of the key difference between galvanic and electrolytic cells, including their spontaneity, energy conversion, power source, electron flow, cell potential, and applications.
Galvanic cells are electrochemical cells that convert chemical energy into electrical energy through spontaneous redox reactions. They consist of two half-cells, each with an electrode immersed in an electrolyte solution. Electrolytic cells, on the other hand, are electrochemical cells that use electrical energy to drive non-spontaneous redox reactions. They operate in the opposite direction of galvanic cells. The external power source provides the necessary energy to force the electrons to move from the anode to the cathode, reversing the natural flow of electrons in the reaction.
FAQs on Difference Between Galvanic and Electrolytic Cell
1. How does a galvanic cell convert chemical energy into electrical energy?
In a galvanic cell, chemical energy is converted into electrical energy through spontaneous redox reactions. The oxidation half-reaction occurs at the anode, where a chemical species loses electrons, releasing energy. Simultaneously, at the cathode, the reduction half-reaction takes place, involving the gain of electrons. The flow of electrons generated by the oxidation-reduction reactions is channelled through an external circuit, creating an electric current. This movement of electrons constitutes the conversion of chemical energy into electrical energy, which can be harnessed for various practical applications.
2. Can an electrolytic cell operate without an electrolyte?
No, an electrolytic cell cannot operate without an electrolyte. The electrolyte is a substance that conducts electric current through the cell. It contains ions that facilitate the flow of electrons during electrolysis. In an electrolytic cell, an external power source is used to drive a non-spontaneous chemical reaction. Without the presence of an electrolyte, there would be no ions available to migrate toward the electrodes and carry the electrical charge.
3. Can a galvanic cell be recharged or reused?
A galvanic cell is designed for one-time use and cannot be recharged or reused in its original form. Once the reactants are consumed, the cell ceases to generate an electric current. Reversing the reactions and restoring the reactants to their original state is not feasible without external intervention. In contrast, rechargeable cells, such as certain types of batteries, are specifically designed for repeated charging and discharging cycles by incorporating reversible redox reactions and suitable electrode materials.
4. How do galvanic and electrolytic cells play a role in energy conversion?
Galvanic cells convert chemical energy into electrical energy by harnessing spontaneous redox reactions. This electrical energy can be utilized to power various devices and systems. On the other hand, electrolytic cells consume electrical energy to drive non-spontaneous redox reactions, facilitating chemical transformations. This allows for the production of valuable substances or the extraction of metals. Both types of cells contribute to the efficient conversion and utilization of energy, enabling applications in batteries, fuel cells, electroplating, and other industrial processes.
5. What happens to the electrodes in a galvanic cell over time?
In a galvanic cell, the electrodes undergo changes over time due to the oxidation and reduction reactions taking place. The anode, where oxidation occurs, gradually experiences corrosion or degradation as the electrode material is consumed. Conversely, at the cathode, where reduction occurs, deposits or buildup may form on the electrode surface. These changes can impact the efficiency and performance of the galvanic cell. Regular maintenance, electrode replacement, or cleaning is often required to ensure optimal operation and prolong the lifespan of the cell.