Electrochemical Cells – Class 12 | Chapter – 3 | Chemistry Short Notes Series PDF for NEET & JEE
Electrochemical Cells: An electrochemical cell is a device that converts chemical energy into electrical energy or vice versa. It consists of two electrodes (a cathode and an anode) that are immersed in an electrolyte solution, which contains ions that can participate in a chemical reaction. When the electrodes are connected by a conductive material (e.g., a wire), electrons flow from the anode to the cathode, generating an electrical current.
Types of Electrochemical Cells
There are several types of electrochemical cells, including:
- Voltaic or Galvanic Cells: These cells use a spontaneous redox reaction to generate electrical energy. A typical example is the zinc-copper cell, where zinc is oxidized at the anode and copper ions are reduced at the cathode.
- Electrolytic Cells: These cells use an external electrical energy source to drive a non-spontaneous redox reaction. Electrolysis of water is an example, where an external voltage is applied to electrodes immersed in water, causing the water to be oxidized at the anode and reduced at the cathode to produce hydrogen and oxygen gases.
- Fuel Cells: Fuel cells convert the chemical energy of a fuel directly into electrical energy without combustion. A hydrogen-oxygen fuel cell is a common example, where hydrogen gas is oxidized at the anode and oxygen gas is reduced at the cathode to produce water and electrical energy.
- Flow Batteries: Flow batteries use two different electrolyte solutions that are pumped through a cell to produce electrical energy. The electrolytes flow through a membrane that separates the anode and cathode compartments. Vanadium redox flow batteries are commonly used in renewable energy applications.
- Lithium-ion Batteries: These are rechargeable batteries commonly used in portable electronics and electric vehicles. They use lithium ions as the charge carriers, which move between the anode and cathode during charging and discharging.
- Lead-acid Batteries: These are commonly used in vehicles and backup power supplies. They use lead and lead dioxide electrodes in sulfuric acid electrolyte.
- Nickel-cadmium Batteries: These are rechargeable batteries that have been commonly used in portable electronics and power tools. They use nickel and cadmium electrodes in an alkaline electrolyte.
- Zinc-carbon Batteries: These are commonly used in household applications such as flashlights and remote controls. They use zinc and carbon electrodes in an acidic electrolyte.
Properties of Electrochemical Cells
Electrochemical cells have several important properties, including:
- Voltage: The voltage produced by an electrochemical cells is a measure of its ability to drive electrons through a circuit. The voltage is determined by the difference in the electrode potentials of the anode and cathode.
- Electrode Potential: The electrode potential is a measure of the tendency of an electrode to lose or gain electrons. It is related to the standard reduction potential of the half-reaction occurring at the electrode.
- Current: The current produced by an electrochemical cells is a measure of the flow of electrons through a circuit. It is determined by the voltage and the resistance of the circuit.
- Power: The power produced by an electrochemical cell is a measure of the rate at which it can do work. It is determined by the voltage and current produced by the cell.
- Efficiency: The efficiency of an electrochemical cell is a measure of how much of the chemical energy is converted into electrical energy. It is determined by the ratio of the electrical energy output to the chemical energy input.
- Capacity: The capacity of an electrochemical cell is a measure of how much charge it can store. It is determined by the amount of active material in the electrodes and the electrolyte.
- Life cycle: The life cycle of an electrochemical cell is a measure of how many charge/discharge cycles it can undergo before its capacity decreases. It depends on the chemical stability of the electrodes and the electrolyte, and the conditions under which the cell is operated.
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