Amount of substance in use in chemical engineering in the United States is the pound-mole, having the symbol lb-mol. One pound-mole is . When quoting an amount of substance, it is necessary to specify the entity involved, unless there is no risk of ambiguity. One mole of chlorine could refer either to chlorine atoms, as in 58.44 g of sodium chloride, or to chlorine molecules, as in 22.711 liters of chlorine gas at STP. The simplest way to avoid ambiguity is to replace the term "substance" by the name of the entity or to quote the empirical formula. For example: Amount of substance
Corrosive substance Corrosive substance A corrosive substance is one that will damage or destroy other substances with which it comes into contact by means of a chemical reaction. The word "corrosive" is derived from the Latin verb "corrodere", which means "to gnaw", indicating how these substances seem to "gnaw" their way through flesh or other materials. The word corrosive refers to any chemical that will dissolve the structure of an object. They can be acids, oxidizers, or bases. When they come in contact with a surface, the surface deteriorates. The deterioration can happen in minutes, e.g. concentrated muriatic acid spilled on skin;