Chemical reactions are processes in which the chemical composition of one or more substances changes. They are characterized by the exchange or rearrangement of electrons between the atoms in the substances involved. Chemical reactions can be spontaneous or driven by an external energy source.

A chemical reaction is characterized by the formation of new compounds and the release of energy, in the form of heat, light or radiation. The speed of a chemical reaction depends on many factors, such as temperature, the concentration of the substances involved and the presence of catalysts.

Chemical reactions are ubiquitous in our environment and play an important role in many areas, such as medicine, the processing and manufacturing of goods, energy production and many others. A better understanding of chemical reactions and their rates is therefore of great importance for solving many scientific and technical problems.