Electrolysis of Water is a process in which water is split into hydrogen and oxygen gas when electricity is passed through it. This process occurs in an electrolyzer, which consists of two electrodes (anode and cathode) submerged in a water-based electrolyte solution.
In this article, we will learn about Electrolysis of Water, Principle and Process of Water Electrolysis, along its advantages.
What is Electrolysis?
The process of decomposing the ionic compound into its constituent elements using electric current is called Electrolysis. In other words, a material can break down into its component components or ions by the chemical process of electrolysis, which involves passing an electric current through the substance.
Electrolysis has many other significant industrial and laboratory uses which include the production of different compounds and the extraction of metals from their ores. To convert electrical energy into chemical energy, electrolysis uses electric energy to propel non-spontaneous processes.
What is Electrolysis of Water?
Water molecules (H2O) are chemically divided into hydrogen gas (H2) and oxygen gas (O2) through a process known as electrolysis. Two electrodes (generally composed of metals like platinum or graphite) submerged in water and linked to a power source comprise an electrolytic cell, which is where this process normally takes place.
Water molecules split into hydrogen ions (H+) and hydroxide ions (OH–) when an electric current flows through them. Hydrogen ions are reduced to produce hydrogen gas at the cathode (negative electrode), and hydroxide ions are oxidized to produce oxygen gas at the anode (positive electrode).
Electrolysis of Water Definition
Electrolysis of water is a chemical process that breaks down water molecules into hydrogen and oxygen gases by means of an electric current.
Water Electrolysis Equation
Following is the chemical formula for electrolyzing water:
2H2O(l) → O2(g) + 2H2(g)
This equation demonstrates how electricity passing through two molecules of water causes them to split into two molecules of hydrogen gas and one molecule of oxygen gas.
Electrolysis of Water
Principle of Electrolysis of Water
Water molecules (H2O) split into hydrogen gas (H2) and oxygen gas (O2) when an electric current flows through them. We refer to this process as the electrolysis of water. This process takes place at electrodes where water molecules split into their component ions.
Application of electricity causes the water in an electrolytic cell, (which has platinum or graphite electrodes), to separate into hydrogen and oxygen gases.
- Water molecules pick up electrons and transform into hydrogen gas at the cathode (negative electrode).
- Water molecules lose electrons at the anode, or positive electrode, and transform into oxygen gas.
- In the end, this procedure separates water into its two constituent parts, oxygen and hydrogen.
Water Electrolysis Equations at Cathode and Anode
Depending on the electrolyte utilized, the reduction of protons (H+) of water molecules (H2O) at the cathode (negative electrode) produces hydrogen gas (H2). At the cathode, the half-reaction is:
2H2O(l) + 2e– → H2(g) + 2OH–
Water molecules [or hydroxide ions (OH–)] oxidize to create oxygen gas (O2) at the anode (positive electrode). At the anode, the half-reaction is:
4OH– → O2(g) + 2H2O(l) + 4e–
The net reaction of water electrolysis is given as:
2H2O(l) → O2(g) + 2H2(g)
Factors Affecting Water Electrolysis
There are various factors that can affect the speed of electrolysis of water, such factors are:
- Addition of Acid
- Addition of Base
- Addition of Salt
- Presence of Electrocataylst
Affect of each of them is given below,
Electrolysis of Water in Presence of Acid
Electrolysis process of water does not change when it is electrolyzed in the presence of acids, such as hydrochloric acid (HCl) or sulfuric acid (H2SO4). Acids, only raise hydrogen ion (H+) concentration in the solution, which speeds up electrolysis process and increases amount of hydrogen gas produced at cathode.
Electrolysis of Water in Presence of Base
Electrolysis of water operates on the same principle as pure water when a base, such as potassium hydroxide (KOH) or sodium hydroxide (NaOH), is present. Concentration of hydroxide ions (OH–) in the solution is increased by bases, which has an impact on the electrolysis process and the solution’s conductivity. A base can increase the amount of hydrogen gas produced at the cathode, just like acids can.
Electrolysis of Water in Presence of Salt
Dissociation of salts into their component ions upon dissolution in water can have an impact on the solution’s conductivity during electrolysis. Salts can modify the electrolysis process by adding more ions to the solution, which could have an impact on the distribution of hydrogen and oxygen gas production at the electrodes.
Water Electrolysis using Electrocatalyst
Materials known as electrocatalysts speed up the necessary chemical processes while requiring less energy to occur, which helps to facilitate the electrolysis process. By encouraging the breakdown of water molecules into hydrogen and oxygen gasses during the electrolysis of water, electrocatalysts can increase the process’ efficiency.
Process of Electrolysis of Water
Utilizing an electric current, water (H2O) is broken down into its component parts, hydrogen (H2) and oxygen (O2), in a process known as electrolysis. This procedure is carried out in an electrolytic cell, which normally consists of two electrodes submerged in an electrolyte solution made of water.
Below is a step-by-step explanation of how water is electrolyzed:
- Configure Electrolytic Cell: A container filled with water is submerged with two electrodes, which are typically composed of inert materials such as platinum or graphite.
- Addition of Electrical Source: A direct current (DC) power source’s terminals are linked to the electrodes.
- Add electrolyte: Even while pure water may perform electrolysis, the process can be improved by adding a little quantity of electrolyte (like sulfuric acid) to increase water conductivity.
- Gathering Gas: After electrolysis, the evolved gasses oxygen and hydrogen are gathered individually.
Reactions using Electrolysis
Reduction takes place at the cathode, or negative electrode. In order to create hydrogen gas, water molecules must absorb electrons and decrease.
2H2O + 2e−→H2 ​ +2OH−
Oxidation takes place at the anode, or positive electrode. After losing electrons, water molecules oxidize to produce positively charged hydrogen ions and oxygen gas.
2H2O → O2 + 4H+ + 4e−
The combination of the reduction and oxidation processes is the overall reaction for the electrolysis of water:
2H2​O → 2H2​ + O2
Note:
- Water has a 2:1 hydrogen to oxygen ratio, meaning that it produces twice as much hydrogen as oxygen.
- Electrolysis process may cause the electrodes to corrode or experience other modifications.
Electrolyzers
Electrolysis is the process of breaking down water (or other compounds) into its component parts by use of an electric current, and electrolyzers are tools used to carry out this process. An external power source provides the electric current for these devices, which normally comprise of two electrodes submerged in an electrolyte solution.
Depending on the use and volume of production, electrolyzers come in a variety of forms and combinations. Their purpose is to effectively produce hydrogen and oxygen gasses from water by electromagnetic separation. In order to produce hydrogen for use in fuel cells, industrial processes, and energy storage applications, they are essential.
Electrolysis of Pure Water
Without the addition of any contaminants or electrolytes, pure water is electrolyzed by running an electric current across it. As per the following chemical equation, water molecules (H2O) undergo breakdown at the cathode, resulting in hydrogen gas (H2) and oxygen gas (O2) at the anode.
2H2O (l) → 2H2 (g) + O2 (g)
In order to learn the fundamentals of electrolysis and to create pure hydrogen and oxygen gasses, pure water electrolysis is frequently utilized in laboratory settings or educational displays.
Electrolysis of Water Advantages
Advantages of water electrolysis are as follow:
- Ecologically Friendly: Water electrolysis is a clean process that doesn’t release any hazardous emissions or toxins, which makes it eco-friendly, especially when it runs on renewable energy.
- Resource Abundance: Since water, the electrolysis’s raw material, is widely accessible and abundant, water electrolysis is a sustainable way to produce hydrogen.
- Versatility: Electrolysis is flexible and less dependent on fossil fuels since it may be carried out using a variety of electrical sources, including renewable energy sources like solar and wind power.
- Superior Purity: Water electrolysis yields hydrogen and oxygen gases of superior quality, which are necessary for a range of commercial and scientific uses, such as chemical synthesis and fuel cells.
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Electrolysis of Water FAQs
What is Water Electrolysis?
Water electrolysis is a chemical process that divides water molecules into hydrogen and oxygen gasses with the use of an electric current.
What are Uses of Water Electrolysis?
Creation of hydrogen for fuel cells, energy storage, chemical synthesis, metal refining, and other industrial processes are the main uses for water electrolysis.
What Elements Influence Electrolysis of Water?
Temperature, pressure, ion concentration, electrode material, current density, electrolyte type, and electrode material are some of the variables that impact water electrolysis.
What are Cathode and Anode Reactions of Electrolysis of Water?
Cathode and Anode Reactions of Water Electrolysis is as follow:
- At Cathode: 2H2O + 2e– → H2 + 2OH–
- At Anode: 2H2O + O2 → 4H+ + 4e–
What is Principle of Water Electrolysis?
Principle of water electrolysis is that the water split into hydrogen and oxygen when electricity is passed through it.
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