Editing Mole (unit) (section)

== Similar units ==
Like chemists, chemical engineers use the unit mole extensively, but different unit multiples may be more suitable for industrial use. For example, the SI unit for volume is the cubic metre, a much larger unit than the commonly used litre in the chemical laboratory. When amount of substance is also expressed in kmol (1000&nbsp;mol) in industrial-scaled processes, the numerical value of molarity remains the same, as <math display="inline">\frac{\text{kmol}}{\text{m}^3}=\frac{1000\text{ mol}}{1000\text{ L}}=\frac{\text{mol}}{\text{L}}</math>. Chemical engineers once used the ''kilogram-mole'' (notation ''kg-mol''), which is defined as the number of entities in 12&nbsp;kg of <sup>12</sup>C, and often referred to the mole as the ''gram-mole'' (notation ''g-mol''), then defined as the number of entities in 12&nbsp;g of <sup>12</sup>C, when dealing with laboratory data.<ref name="Himmelblau">{{cite book |last=Himmelblau |first=David |title=Basic Principles and Calculations in Chemical Engineering |year=1996 |isbn=978-0-13-305798-0 |edition=6 |pages=17–20|publisher=Prentice Hall PTR }}</ref>

Late 20th-century chemical engineering practice came to use the ''kilomole'' (kmol), which was numerically identical to the kilogram-mole (until the [[2019 revision of the SI]], which redefined the mole by fixing the value of the Avogadro constant, making it very nearly equivalent to but no longer exactly equal to the gram-mole), but whose name and symbol adopt the SI convention for standard multiples of metric units – thus, kmol means 1000&nbsp;mol. This is equivalent to the use of kg instead of g. The use of kmol is not only for "magnitude convenience" but also makes the equations used for modelling chemical engineering systems [[Coherence (units of measurement)|coherent]]. For example, the conversion of a flowrate of kg/s to kmol/s only requires dividing by the molar mass in g/mol (as <math display="inline">\frac{\text{kg}}{\text{kmol}}=\frac{1000\text{ g}}{1000\text{ mol}}=\frac{\text{g}}{\text{mol}}</math>) without multiplying by 1000 unless the basic SI unit of mol/s were to be used, which would otherwise require the molar mass to be converted to kg/mol.

For convenience in avoiding conversions in the [[Imperial units|imperial]] (or [[United States customary units|US customary units]]), some engineers adopted the ''pound-mole'' (notation ''lb-mol'' or ''lbmol''), which is defined as the number of entities in 12&nbsp;[[Pound (mass)|lb]] of <sup>12</sup>C. One lb-mol is equal to {{val|453.59237|u=g-mol}},<ref name="Himmelblau" /> which is the same numerical value as the number of grams in an [[international avoirdupois pound]].

Greenhouse and growth chamber lighting for plants is sometimes expressed in micromoles per square metre per second, where 1&nbsp;mol photons ≈ {{val|6.02|e=23}} photons.<ref>{{cite web|title=Lighting Radiation Conversion|url=http://www.egc.com/useful_info_lighting.php|access-date=March 10, 2016|url-status=live|archive-url=https://web.archive.org/web/20160311131342/http://www.egc.com/useful_info_lighting.php|archive-date=March 11, 2016}}</ref> The obsolete unit [[Einstein (unit)|einstein]] is variously defined as the energy in one mole of photons and also as simply one mole of photons.