Self-Instruct
Introduction:
Modern life is unthinkable without the presence of cell batteries. These tiny yet powerful devices help to power products ranging from simple toys to advanced medical equipment. While many types of cells exist, two of the most popular are the dry cell and mercury cell. Both cells have different construction materials and chemical reactions, leading to different electric properties. This article sets out to explain the key differences between the dry cell and mercury cell and how they function.
Dry Cell:
The dry cell is the most commonly used battery type, found in everyday items such as flashlights, portable radios, and electronic toys. The dry cell is a self-contained battery, with all the components sealed within an outer casing. The outer casing is usually made of zinc or plastic and contains a carbon rod surrounded by a mixture of manganese dioxide, ammonium chloride, and zinc chloride. The mixture is held in place by a paper or fiberglass separator, which prevents internal damage from short circuits. At the bottom of the cell, there is a plug that serves as the negative terminal, while the top is the positive terminal.
The cell's central element is the carbon rod or electrode, which acts as the cathode. The manganese dioxide serves as the anode. When the dry cell is in use, the ammonium chloride electrolyte inside the cell breaks down into positively charged hydrogen ions and negatively charged chloride ions. These ions start to move towards the carbon rod and the zinc casing. The hydrogen ions are attracted to the carbon rod and form an electrochemical reaction that releases electrons, which move from the carbon rod, down through the paper or fiberglass separator, to the zinc casing. This creates an electric current that allows the device to operate.
The dry cell battery has a long shelf life and can run for a long time before its power runs out. They can last for many years and are generally sturdy enough to withstand rough handling. Dry cell batteries are also ideal for portable devices, as they are small, lightweight, and relatively cheap.
Mercury Cell:
The mercury cell was once one of the most popular battery types. However, due to environmental concerns and the toxicity of mercury, this type of cell has been largely phased out of use. In mercury cells, the negative electrode is made of zinc, while the positive electrode is made of mercury oxide with cadmium oxide added as a stabilizer. The electrolyte is a mixture of potassium hydroxide and mercury oxide, which produces an electrochemical reaction that creates an electric current.
When the mercury cell is in use, the electrolyte breaks down, creating hydroxide and mercury amalgam. The mercury amalgam is then oxidized, creating a current that moves from the positive electrode to the negative electrode. The process produces a significant amount of heat, and the reaction is continuous until the electrolyte has been consumed. Overall, the mercury cell has a low internal resistance, which makes it ideal for devices that require high amounts of power in a short period.
Difference between dry cell and mercury cell:
The primary difference between the dry cell and mercury cell is the chemical composition of their components. The dry cell is made up of a carbon rod, enclosed in a zinc or plastic casing, with a mixture of manganese dioxide, ammonium chloride, and zinc chloride, acting as the electrolyte. In contrast, the mercury cell uses mercury oxide and cadmium oxide as the positive electrode, with potassium hydroxide and mercury oxide serving as the electrolyte. The mercury cell also has a negative electrode made up of zinc.
Another significant difference between the two is their electrical properties. The dry cell has a higher internal resistance than the mercury cell. This means that the dry cell is better suited for devices that require small amounts of current at a continuous rate. In contrast, the mercury cell has a lower internal resistance, making it better suited for devices that require high amounts of current in a short period.
The environmental impact of these two batteries is another critical difference. The mercury cell contains a hazardous material (mercury), making it a severe environmental concern due to its toxic nature. The dry cell, on the other hand, is a safer and more environmentally friendly option. The dry cell is also more versatile since they can be manufactured in various sizes, including AA, AAA, 9V, C, and D sizes. There are other variations of dry cells, including Lithium-ion, Nickel-Cadmium, and Nickel-Metal Hydride.
Conclusion:
The dry cell and mercury cell are two of the most common battery types used in portable electronic devices. While both cells function by producing an electrochemical reaction, they have different properties, making them better suited for different purposes. The dry cell is more common due to its safer and more versatile nature. At the same time, the mercury cell is still in use, albeit in a smaller capacity, in specific high-powered applications. With the rise of newer and more efficient battery types, such as the Lithium-ion, the use of dry and mercury cells may decrease even further in the future. However, for now, both cells still hold some significance in the powering of everyday devices.