Electrolysis is a process of decomposing ionic compounds into elements by transiting a direct current through a compound in liquid form. In general words, it is a process of converting compound ions in a liquid state into their oxidized or reduced state by passing an electric current through the compound. The anions are oxidized at the anode, and cations are reduced at the cathode.
Michael Faraday first popularized the term "Electrolysis" in the 19th century. The electrolysis process helped chemical reactions study in obtaining the pure elements. Currently, the process is commercially essential as it is extensively used in separating or getting pure elements from naturally occurring sources.
For instance, a salt containing water or acidification can be decomposed by passing electric current to original elements oxygen and hydrogen. Also, molten sodium chloride can be decomposed into chlorine and sodium atoms.
The process usually occurs in a vessel called an "Electrolytic cell" comprising two electrodes, anode, and cathode, linked directly to a direct current source. An electrolyte is an ionic compound undergoing decomposition in either a dissolves state or a molten form.
Electrolytic process
There is an interchange of atoms and ions in an electrolytic process due to the removal or addition of electrons from an external circuit. On passing the current, the cations move to the cathode and take electrons from the cathode, and are then discharged into the neutral atom.
The neutral atom moves upwards, if gas, and deposited on the cathode if solid. This is known as a reduction process, and the cation is reduced at the cathode.
At the same time, if we talk about anions, they give up their extra electrons to anode and are oxidized to neutral atoms at the anode. Electrons unconfined by anions travel across the electrical circuit and reach the cathode completing the circuit.
Electrolysis includes a simultaneous reduction reaction at the cathode and oxidation reaction at the anode.
For instance, when an electric current is passed via molten sodium chloride, the chloride ion reaches the anode, gives its electrons, and becomes a chlorine atom to form a chlorine molecule. In contrast, the sodium ion is attracted by the cathode from which it takes an electrode and becomes a sodium atom.
Na+ in electrolyte + e- (from cathode) ------> Na at the cathode
Cl- from electrolyte -----> e- + Cl ---------> Cl2 at the anode
While the electrolysis process is useful to get the elemental forms from the compounds directly, it can also be indirectly used in alkali's metallurgy and alkaline earth metals, metal purification, metals decomposition, etc.
Electrolysis Product
Electrolysis of two ions, namely cation and anion present in a single electrolyte, is direct and Electrolysis produces the products present in a compound. When more than one anion or cation is present, each of the ions will compete for oxidation and reductions.
Factors affecting Electrolysis Process
Several factors may affect the electrolysis process. This includes:
- Electrode's nature
- Nature and state of electrolyte
- Overvoltage at electrodes
- Electrode potential and nature of ions present in the electrolyte
Applications of Electrolysis
Electrolysis has many applications in both industrial and experimental products. A few essential applications are
- Metals Purification
- Alkali's metallurgy and alkaline earth metals.
- Manufacture of pure gases
- Determination of equivalent eight substances
- Compounds manufacture like sodium carbonate, sodium hydroxide, etc
- Electroplating for corrosion resistance.
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