Formas de expresar la composición química en el SI

Due to wide range and complexity of materials and chemicals, several quantities are normally used to express the chemical composition of mixtures. Nevertheless, during years those quantities have been reviewed in the frame of the International System of Units (SI) by international organizations related to chemical sciences and a set of quantities with unified nomenclature and notation has been proposed to express chemical composition. Important concepts related to chemical measurements like uncertainty and traceability are discussed to aim correct use and understanding of quantities and units of composition. A brief description of SI units and writing rules are also included.