Chemical reactions

Chemical reactions are processes in which the atoms of reactants are rearranged to form new molecules or compounds. These processes are fundamental in chemistry and in everyday life.

A chemical reaction can be classified into different types, depending on the nature of the reactants and products, and the way in which the transformation is carried out. Some of the most common types are:

Synthesis or combination reactions. Two or more reactants combine to form a single product. For example, the synthesis of water from hydrogen and oxygen.

Decomposition reactions. A single reactant is split into two or more products. For example, the decomposition of hydrogen peroxide into water and oxygen.

Substitution or displacement reactions. One element or functional group of a reactant is replaced by another element or functional group. For example, the reaction of an acid with a metal to form a salt and release hydrogen.

Oxidation-reduction reactions. A transfer of electrons occurs between the reactants, and may involve the gain or loss of electrons. For example, the oxidation of iron in the presence of oxygen to form iron oxide.

Precipitation reactions. A solid is formed from aqueous solutions.

Acid-base reactions. A proton transfer occurs between the reactants.

Each type of chemical reaction has specific characteristics. For example, synthesis reactions tend to be exothermic, while decomposition reactions tend to be endothermic.