Direct combination or synthesis

Direct combination or synthesis: in which 2 or more chemical elements or compounds unite to form a more complex product: N2 + 3 H2 → 2 NH3

A chemical synthesis begins by selection of compounds that are known as reagents or reactants. Various reaction types can be applied to these to synthesize the product, or an intermediate product. This requires mixing the compounds in a reaction vessel such as a chemical reactor or a simple round-bottom flask. Many reactions require some form of work-up procedure before the final product is isolated.