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The process of water electrolysis happens when water is decomposed into hydrogen and oxygen gas with the help of an electric current. This process has become popular particularly in industries requiring hydrogen in their operations.
The process is made this way- a typical electrical power source is linked to a couple of electrodes or plates which are placed in water. The plates or electrodes are usually manufactured from inert metal like stainless steel and platinum. Hydrogen will then come out of the cathode, or negatively charged electrodes. On the other hand, the oxygen will come out of the anode or positively charged electrodes. The amount of oxygen produced is double the amount of the oxygen, although both are relative to the entire electrical charge processed through the water.
The electrolysis of water is a slow process, and it can only transpire with self-ionization of water. Also, pure water boasts of an electrical conductivity of about one millionth of seawater. Water electrolysis is even made faster by the addition of electrolyte such as base, acid, or salt.
One of the products of water electrolysis is hydrogen gas. This happens during a reduction reaction, when electrons from the cathode are given off to hydrogen cations. Oxygen gas, meanwhile, is formed when oxidation reaction happens, which give electrons to the anode.
In the electrolysis process, the quantity of hydrogen molecules that is produced is twice the quantity of oxygen molecules. Produced gas, therefore, has double the volume of the oxygen gas, assuming the pressure and temperature for both gases are equal.
Adding a water-soluble electrolyte would result to a rise in the conductivity of water. The electrolyte detaches into anions and cations. The former rushes to the anodes, while the cations rush to the cathode. Both allow the continued electricity flow.
Caution must be taken in selecting an electrolyte, since anions from electrolyte compete with hydroxide ions in giving up electrolyte. Electrolyte anion with smaller standard electrode potential compared to hydroxide will instead be oxidized, hence there is no production of oxygen gas. Similarly, cation with higher electrode potential compared to hydrogen ion would be reduced, hence no hydrogen gas.
Some of the cations listed have a smaller electrode potential than hydrogen ion and are suited as electrolyte cations: Na+, Li+, K+, C+, and Ca2+.
Strong acids like sulfuric acid as well as strong bases like potassium hydroxide are commonly used as electrolytes.
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