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The study of electricity and how it affects chemical reactions is known as electrochemistry. The movement of electrons from one element to another in a redox or oxidation-reduction reaction generates electricity in electrochemistry. Electrochemical cells that generate an electric current are known as voltaic or galvanic cells, whereas those that generate chemical processes, such as by electrolysis, are known as electrolytic cells.
Galvanic cells:
A galvanic cell is an electrochemical cell that generates electricity by transferring electrons in redox processes. This cell is powered by a chemical process that occurs spontaneously and generates an electric current through an external connection. The energy produced by galvanic cell reactions is used to accomplish work. Galvanic cells are often utilised as batteries as a result of this. The term “battery” has come to refer to a single galvanic cell in the real world, while a genuine battery is made up of several cells.
Galvanic cells while electrical energy:
An electric current is created when electrons are liberated at the anode and move across the wire. As a result, galvanic cells convert chemical energy into electrical energy, which may subsequently be employed to do work.
Functions of Galvanic cell:
1) The oxidation and reduction reactions are carried out in two different types of half-cells.
2) In these cells, the anode is considered to be negative, while the cathode is believed to be positive.
Electrolytic cells:
Electrical energy is converted into chemical potential energy by electrolytic cells. Electrolysis is the name of the procedure. Usually, the goal is to transform reactants into more valuable products. One of two types of electrochemical cells is the electrolytic cell.
Applications of Electrolytic cells:
Electrolytic cells are used for a variety of purposes, including electroplating metals, battery charging, and isolating pure metals from metallic compounds.
Difference between Galvanic cells and Electrolytic cell:
Galvanic cells | Electrolytic cells |
1)In galvanic cells, spontaneous redox processes allow for continuous electron flow via the conductor, converting chemical energy to electric energy.
| Under the influence of an external source, redox processes occur in an electrolytic cell, where electricity is converted into chemical energy. |
2)Galvanic cells use chemical reactions to generate electricity.
| Electrolytic cells use an electric current to conduct a chemical reaction while using an external source. |
3)Galvanic cells are made up of two electrodes that are separated by a semipermeable membrane or a salt bridge and are immersed in ion solutions.
| A DC source and an electrolytic container with two electrodes make up electrolytic cells. A melt or an aqueous solution of salt, acid, or alkali can be used as the electrolyte. |
4)The anode is the negative electrode in galvanic cells, whereas the cathode is the positive electrode. | The opposite is true with electrolytic cells. |
5)The oxidation reaction in a galvanic cell occurs at the anode (negative electrode), where there is an excess of negative charge. The reduction reaction occurs at the cathode, causing a positive charge accumulation. | An external source is utilised to initiate a reaction in an electrolytic cell. The electrons are forced out of the negative electrode, which is where the reduction phase will take place. The oxidation phase takes place on the positive electrode, which is the anode. |
6)Galvanic cells are usually referred to as batteries or accumulators since they are employed as a source of electrical current. | Electrolytic cells have a variety of applications, including producing hydrogen and oxygen gas for commercial and industrial use, electroplating, and extracting pure metals from alloys, among others.
|
Salt Bridge:
A critical component of any voltaic or galvanic electrochemical cell is the salt bridge. It’s usually a tube with electrolytic solutions like potassium chloride (KCl) or other chlorides in it. The bridge’s role is to keep the cell electrically neutral while permitting free passage of ions throughout, preventing electron build-up in the half-cells, which would cause processes to halt. The salt bridge is often an inverted glass U-shaped tube filled with sodium chloride in empirical settings. To form an electrochemical cell, its two legs dip into two independent electrolyte vessels (half-cells).
Functions of salt bridge:
- Between the two half cells, a salt bridge serves as an electrical contact.
It blocks the mechanical flow of solution but allows ions to migrate freely, allowing an electric current to pass through the electrolyte solution.
- It stops charges from building up.
- A salt bridge keeps the charge balance in the two half cells in check.
- The liquid connection potential is reduced or eliminated by using a salt bridge.
Conclusion:
An electrochemical cell is made up of two electrodes or half-cells that are connected by an electrolyte (ionic conductor). If half-cells are separated, a salt bridge can be used to connect them (concentrated solution of electrolytes in agar-agar gel). The galvanic cell generates electricity through a chemical reaction that occurs spontaneously within it. The electrolytic cell, on the other hand, produces a chemical change as a result of the current. The cell must undergo spontaneous chemical change in order to be galvanic.
