Electrochemical Cell vs Galvanic Cell | Voltaic Cells vs Electrochemical Cells
In electro chemistry oxidation, reduction reactions play an important role. In an oxidation-reduction reaction, electrons are transferring from one reactant to another. The substance that accepts electrons is known as a reducing agent, where as the substance which gives away the electron is known as the oxidizing agent. Reducing agent is responsible for reducing the other reactant while undergoing oxidation itself, and for oxidizing agent, it is vice versa. These reactions can be divided into two half reactions, to show separate oxidations and reductions; thus, it shows the number of electrons moving in or out.
Electrochemical cell is a combination of a reducing and oxidizing agent, which is physically separated from each other. Usually separation is done by a salt bridge. Although they are physically separated, both half-cells are in chemical contact with each other. Electrolytic and galvanic cells are two types of electrochemical cells. In both electrolytic and galvanic cells, oxidation-reduction reactions are taking place. Therefore, in an electrochemical cell, there are two electrodes called an anode and a cathode. Both electrodes are externally connected with a high resistant voltmeter; therefore, current will not be transmitting between the electrodes. This voltmeter helps to maintain a certain voltage between the electrodes where oxidation reactions takes place. Oxidation reaction takes place on the anode, and the reduction reaction takes place on the cathode. Electrodes are immersed in separate electrolyte solutions. Normally, these solutions are ionic solutions related to the type of electrode. For example, copper electrodes are immersed in copper sulfate solutions and silver electrodes are immersed in silver chloride solution. These solutions are different; hence, they have to be separated. The most common way to separate them is a salt bridge. In an electrochemical cell, the potential energy of the cell is converted to an electrical current, which we can use to light a bulb, or to do some other electrical work.
Galvanic or voltaic cells store electrical energy. Batteries are made from a series of galvanic cells, to produce a higher voltage. The reactions at the two electrodes in Galvanic cells tend to proceed spontaneously. When the reactions are taking place, there is a flow of electrons from the anode to the cathode via an external conductor. For example, if the two electrodes are silver and copper in a Galvanic cell, the silver electrode is positive with respect to the copper electrode. The copper electrode is the anode, and it undergoes oxidation reaction and release electrons. These electrons go to the silver cathode via the external circuit. Hence, silver cathode undergoes reduction reaction. A potential difference is generated between the two electrodes, which allow the electron flow. Following is the spontaneous cell reaction of the above Galvanic cell.
2 Ag+ (aq) + Cu(s) ⇌ 2Ag (s) + Cu2+ (aq)
What is the difference between Electrochemical Cell and Galvanic Cell?
• Galvanic cell is a type of electrochemical cell.
• Galvanic cell stores electrical energy and the reactions at the two electrodes in Galvanic cells tend to proceed spontaneously.
• Compared to other electrochemical cells, in Galvanic cell, electrons flow from the anode to the cathode via an external conductor.