Corrosive substance or slowly over days or years, e.g. the rusting of iron in a bridge. Sometimes the word caustic is used as a synonym for "corrosive", but "caustic" refers only to strong bases, particularly alkalis, and not to acids, oxidizers, or other non-alkaline corrosives. At low concentrations, a corrosive substance is called an irritant, and its effect on living tissue is called irritation. At high concentrations, a corrosive substance causes a chemical burn, a distinct type of tissue damage. Corrosives are different from poisons in that corrosives are immediately dangerous to the tissues they contact, whereas poisons may have systemic toxic
Chemical composition Chemical composition Chemical composition refers to the identity and relative number of the chemical elements that make up any particular compound. The chemical composition of a pure substance corresponds to the relative amounts of the elements that constitute the substance itself. It can be expressed with a chemical formula, such as an empirical or molecular formula. For example, the chemical formula for water is HO: this means that each molecule of water is constituted by 2 atoms of hydrogen (H) and 1 atom of oxygen (O). Thus the chemical composition of water may be interpreted as a 2:1 ratio of