The electrolytic cell converts electrical energy in to chemical energy, thus the electrodes must be conductive. Electrolysis is a method used for extraction of specific metals from ores, purification of metals, production of gases and electroplating (Chemindustry, 2014). Electroplating is the process of metal being deposited from one electrode to another in an electrolytic cell. Commercially, electroplating is used for coating a thin layer on a metal to attain durability or aesthetics. .
In the process of electroplating, the objective of the technique is to coat a layer of metal on to another metal, the coated metal is the cathode and the anode is the provider of this layer. The atoms which are plated are transferred from the electrolyte solution, therefore, to attain a particular coat the electrolyte must be the salt product of the cathode (Anon., 2016). The potential difference is controlled in the plating process; a low amount of constant voltage is preferable as it provides enough efficiency of metal deposition however, does not distribute enough energy to cause a large sub-reaction with the water molecules of the electrolyte solution. Although when a potential difference is applied the dominant reaction occurs between the electrodes, hydrogen can also be liberated from the water. For example, if there was not a metallic ion close to the cathode and the electrons had built up due to constant current; the electrons would bond to the water molecules and produce hydrogen gas (T Mooney, 2011). Refer to figure 1 for half reaction of this process. Products of sub-reactions can damage the metal and also cause discrepancy within the cell, this has an impact on a cells efficiency.
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Figure 1.
An example of electroplating would be copper being coated on to a conductive metal with the electrolyte solution as copper sulphate. As an electrolyte, copper sulphate dissolved in water, dissociates in to separate ions, (cation) and (anion) and moves freely.