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
Work (physics) "weight "lifted" through a height", which is based on the use of early steam engines to lift buckets of water out of flooded ore mines. According to Dugas, it is to Solomon of Caux "that we owe the term "work" in the sense that it is used in mechanics now". The SI unit of work is the joule (J). The SI unit of work is the joule (J), which is defined as the work expended by a force of one newton through a displacement of one metre. The dimensionally equivalent newton-metre (N⋅m) is sometimes used as the measuring unit for