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
Compound (fortification) Compound (fortification) In military science, a compound is a type of fortification made up of walls or fences surrounding several buildings in the center of a large piece of land. The walls can either serve the purpose of being tall, thick, and impenetrable, in which case they would be made of wood, stone, or some other like substance; or dangerous to attempt to scale, in which case they could be made of barbed wire or electrified. Compounds can be designed to double as living spaces and military structures in the middle of hostile territory or as a military area within