Chemical compounds

A chemical compound is defined as a homogeneous substance whose smallest units – such as molecules, ionic complexes or crystal units – consist of at least two different chemical elements present in a fixed stoichiometric ratio. This ratio is determined by chemical bonds (covalent, ionic, metallic or coordinate) and can be expressed in a chemical formula.

Chemical compounds possess characteristic physical and chemical properties that differ significantly from those of the constituent elements, such as melting point, solubility or reactivity. In process engineering mixtures, chemical compounds are usually present as crystalline solids, liquids or dissolved species. Depending on their reactivity, these can exert a chemically neutral, corrosive or otherwise ‘chemically aggressive’ effect on plant equipment.