Electrochemistry. Electrochemical cells and water electrolysis

17/04/2026

The online electrochemistry simulations on this page will help you discover this important branch of chemistry, which has such interesting applications as electric batteries or water electrolysis. We will also discover what electrochemical cells are and their two types: galvanic cells and electrolytic cells.

This Thematic Unit is part of our Chemistry collection

Atmospheric Corrosion

Spontaneous deterioration of a metal by the formation of an accidental galvanic cell with oxidizing agents from the environment.

Decomposition Potential

Minimum external voltage that must be applied to an electrolytic cell for electrolysis to occur continuously.

Electrochemistry

Discipline studying the reciprocal transformation between chemical and electrical energy through electronic transfer processes.

Electrodeposition

Process in which an electric current reduces metal ions in solution to form a solid coating on an electrode.

Electrolysis

Chemical decomposition phenomenon induced by an external electric current passing through an electrolyte.

Electrolytic Cell

Electrochemical system that consumes electrical energy to induce a non-spontaneous chemical reaction where the Gibbs free energy change is greater than zero.

Iontophoresis

Electrochemical application using low-intensity electric current to drive ions through a membrane or the skin.

Overpotential

Excess voltage required, beyond the thermodynamic potential, to overcome the kinetic barriers of a reaction at the electrode.

What is electrochemistry?

Electrochemistry is a branch of chemistry that studies chemical reactions involving electron transfer, i.e. the conversion of chemical energy into electrical energy and vice versa. These reactions occur in systems called electrochemical cells, which consist of two electrodes immersed in a conductive solution called electrolyte.

Electrochemical cells

In an electrochemical cell, the electrodes are composed of conductive materials, such as metals or semiconductors, and are connected through an external circuit. During the reaction, electrons are transferred from one electrode to another through the external circuit, while ions move through the electrolyte to maintain charge neutrality.

There are two main types of electrochemical cells: galvanic cells (also known as batteries) and electrolytic cells.

Galvanic cells

In a galvanic cell, the spontaneous chemical reaction generates electricity. This is the principle used in common batteries, such as alkaline or lithium-ion batteries.

Electrolytic cells

On the other hand, electrolytic cells are devices in which an external electric current is applied to force a non-spontaneous chemical reaction. This process is used in electrolysis, where the components of a substance can be separated by applying an electric current, as in obtaining metals from their compounds or in the production of gases such as hydrogen and oxygen from water.

Applications of electrochemistry

Electrochemistry has applications in many fields. In industry, for example, it is used for metal production, electroplating and surface coating. In the field of energy, electrochemistry is central to the generation and storage of energy in rechargeable batteries and fuel cell technology. In addition, electrochemistry plays an essential role in the research and development of new materials and in catalysis, which is the increase in the rate of chemical reactions by involving electrochemical catalysts.

Atmospheric Corrosion

Spontaneous deterioration of a metal by the formation of an accidental galvanic cell with oxidizing agents from the environment.

Decomposition Potential

Minimum external voltage that must be applied to an electrolytic cell for electrolysis to occur continuously.

Electrochemistry

Discipline studying the reciprocal transformation between chemical and electrical energy through electronic transfer processes.

Electrodeposition

Process in which an electric current reduces metal ions in solution to form a solid coating on an electrode.

Electrolysis

Chemical decomposition phenomenon induced by an external electric current passing through an electrolyte.

Electrolytic Cell

Electrochemical system that consumes electrical energy to induce a non-spontaneous chemical reaction where the Gibbs free energy change is greater than zero.

Iontophoresis

Electrochemical application using low-intensity electric current to drive ions through a membrane or the skin.

Overpotential

Excess voltage required, beyond the thermodynamic potential, to overcome the kinetic barriers of a reaction at the electrode.

Explore the exciting STEM world with our free, online, simulations and accompanying companion courses! With them you’ll be able to experience and learn hands-on. Take this opportunity to immerse yourself in virtual experiences while advancing your education – awaken your scientific curiosity and discover all that the STEM world has to offer!

Electrochemistry simulations

Electrolysis
Electroplating
Potential
Polarity
Polarity II

Electrolysis of water

Electrolysis of water is the decomposition of water (H2O) into the gases oxygen (O2) and hydrogen (H2) by means of a direct electric current. To reduce the resistance to the passage of current through water, it is usually acidified by adding a small amount of sulfuric acid or by adding a strong electrolyte such as sodium hydroxide, NaOH.

Electroplating

Electroplating is an electrochemical treatment consisting of coating a metal surface with cations of another metal contained in an aqueous solution.

Standard reduction potential

The standard reduction potential is the potential of the electrode with respect to the standard hydrogen electrode. The more positive (+) the standard reduction potential, the easier it is to accept electrons than hydrogen ions. Check in the simulation what happens when the electrodes are changed.

Polar and non-polar molecules

A polar molecule is a molecule with a non-uniform distribution of electric charge, resulting in it having a plus and a minus end, e.g. water. A non-polar molecule is a molecule with a uniform distribution of electric charge, resulting in it not reacting in the presence of electric fields, e.g. an oil.

Molecule polarity

When is a molecule polar? Change the electronegativity of the atoms in a molecule to see how it affects polarity. See how the molecule behaves in an electric field. Change the bond angle to see how it affects the polarity shape.

Giants of science

“If I have seen further, it is by standing on the shoulders of giants”

Isaac Newton

Amedeo Avogadro

1776

–

1856

Amedeo Avogadro stated his famous hypothesis: equal volumes of gases, under the same conditions, contain the same number of molecules. He grounded modern chemistry and molecular theory

“In science, patience and method always triumph over chance”

Michael Faraday

1791

–

1867

Michael Faraday discovered electromagnetic induction, conducted pioneering experiments in optics (Faraday effect), and established fundamental principles of electrochemistry.

“Nothing is too wonderful to be true”

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Giants of science

“If I have seen further, it is by standing on the shoulders of giants”

Isaac Newton

Gilbert Newton Lewis

1875

–

1946

Gilbert Lewis formulated the chemical bond theory, introduced electron pairs, and contributed to acid-base theory

“Atoms build nature as bricks build a building”

Michael Faraday

1791

–

1867

Michael Faraday discovered electromagnetic induction, conducted pioneering experiments in optics (Faraday effect), and established fundamental principles of electrochemistry.

“Nothing is too wonderful to be true”

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Test your knowledge

What is electrochemistry, and what processes does it study?

Electrochemistry is the branch of chemistry that examines reactions involving the transfer of electrons, allowing chemical energy to be converted into electrical energy and vice versa. These reactions take place in electrochemical cells, which consist of two electrodes immersed in an electrolyte. During the process, electrons move through an external circuit, while ions travel through the electrolyte to maintain charge balance. Electrochemistry studies both spontaneous reactions, such as those occurring in galvanic cells, and non‑spontaneous reactions that require external energy, characteristic of electrolytic cells. Its scope includes essential phenomena such as corrosion, electrolysis, battery operation and electrochemical catalysis. Through electrochemistry, we understand key processes in energy storage, industrial production and the development of new materials.

How do galvanic and electrolytic cells work, and what differences do they present?

Galvanic and electrolytic cells are electrochemical systems that operate through electron transfer, but they function in opposite ways. In a galvanic cell, the chemical reaction is spontaneous and generates an electric current. Electrons flow from the anode, where oxidation occurs, to the cathode, where reduction takes place. This principle underlies the operation of batteries. In contrast, electrolytic cells require an external power source to drive a non‑spontaneous reaction. The applied current forces chemical changes, such as decomposing substances during electrolysis or extracting metals from their compounds. The essential difference lies in energy flow: galvanic cells produce electricity, while electrolytic cells consume it to induce chemical transformations.

What is electrochemistry used for in everyday life?

Electrochemistry appears in many devices and processes we rely on daily. Batteries in remote controls, smartphones or cars work because chemical reactions inside them generate electricity. Electrochemistry is also used to coat metals and protect them from corrosion, as seen in tools, appliances or car parts. In industry, it helps obtain pure metals and produce substances like chlorine or hydrogen. Even modern clean‑energy technologies, such as fuel cells, depend on electrochemical principles. It is a practical science with a direct impact on how we store energy, protect materials and manufacture essential products.

What is the difference between a galvanic cell and an electrolytic cell?

A galvanic cell produces electricity from a spontaneous chemical reaction. This is what happens in batteries: electrons move through the circuit and generate current without needing external energy. An electrolytic cell, on the other hand, requires electricity to be supplied from outside in order to force a reaction to occur. This is used to separate substances or coat metals through electrolysis. The key difference is that one generates energy while the other consumes it to drive a chemical change.

What happens inside an electrochemical cell when it operates?

Inside an electrochemical cell, electrons travel through an external circuit from one electrode to the other. Meanwhile, ions in the electrolyte move to balance charges and allow the reaction to continue. Oxidation takes place at the anode, where a material loses electrons, and reduction occurs at the cathode, where those electrons are accepted. This coordinated movement of electrons and ions is what enables the cell to generate or use electricity, depending on whether it is galvanic or electrolytic.