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The mole (symbol mol) is the unit of measurement for amount of substance, a quantity proportional to the number of elementary entities of a substance. It is a base unit in the International System of Units (SI). One mole contains exactly 6.02214076×1023 elementary entities (approximately 602 sextillion or 602 billion times a trillion), which can be atoms, molecules, ions, or other particles. The number of particles in a mole is the Avogadro number (symbol N0) and the numerical value of the Avogadro constant (symbol NA) expressed in mol-1. The value was chosen based on the historical definition of the mole as the amount of substance that corresponds to the number of atoms in 12 grams of 12C, which made the mass of a mole of a compound expressed in grams numerically equal to the average molecular mass of the compound expressed in daltons. With the 2019 redefinition of the SI base units, the numerical equivalence is now only approximate but may be assumed for all practical purposes.
The slug is a derived unit of mass in a weight-based system of measures, most notably within the British Imperial measurement system and the United States customary measures system. Systems of measure either define mass and derive a force unit or define a base force and derive a mass unit. A slug is defined as a mass that is accelerated by 1 ft/s2 when a net force of one pound (lbf) is exerted on it.
The units of measurement of German-speaking countries consist of a variety of units, with varying local standard definitions. While many were made redundant with the introduction of the metric system, some of these units are still used in everyday speech and even in stores and on street markets as shorthand for similar amounts in the metric system. For example, some customers ask for one pound of something when they want 500 grams.
A number of different units of measurement have been used in Ethiopia. The values of most of these units are not well defined. In 1963, Ethiopia adopted the metric system.
This is a list of Algerian units of measurement that were used before 1843 for things like length, mass and capacity. After that, Algeria adopted the French system of units.
A number of different units of measurement were used in Chile to measure quantities like length, mass, area, capacity, etc. From 1848, the metric system has been compulsory in Chile.
A number of units of measurement were used in Costa Rica to measure measurements in length, mass, area, capacity, etc. In Costa Rica, metric system has been adopted since 1910, and has been compulsory since 1912, by a joint convention among Costa Rica, Guatemala, Honduras, Nicaragua and Salvador.
A number of different units of measurement were historically used in Cyprus to measure quantities like length, mass, area and capacity. Before the Metric system, the Imperial system was used. In between 1986-1988, metric system was adopted in Cyprus.
A number of units of measurement were used in Egypt to measure length, mass, area, capacity, etc. In Egypt, the metric system was made optional in 1873 and has been compulsory in government use since 1891.
A number of units of measurement were used in Estonia to measure length, mass, area, capacity, etc.
Traditional Greek units of measurement were standardized and used in modern Greece before and alongside the adoption of the metric system in 1836. Metric units were finally made legally compulsory in 1922.
A number of units of measurement were used in Guinea to measure length, mass, etc. Since 1910, the metric system has been compulsory in Guinea.
A number of units of measurement were used in Iceland to measure length, mass, area, capacity, etc. Since 1907, the metric system has been compulsory in Iceland.
A number of units of measurement have been used in Cambodia to measure length, mass, volume, etc. The metric system has been compulsory there since 1914.
A number of units of measurement were used in Indonesia to measure length, mass, capacity, etc. Metric system adopted in 1923 and has been compulsory in Indonesia since 1938.
A number of units of measurement were used in Mexico to measure length, mass, area, capacity, etc. The Metric system was optional from 1857, and has been compulsory since 1896.
A number of units of measurement were used in Switzerland to measure length, mass, etc. Metric system was optional in 1868, and has been compulsory since 1877.
A number of units of measurement were used in Syria to measure length, mass, capacity, etc. The metric system was adopted in 1935 in Syria.
A number of different units of measurement were used in Libya to measure length, mass, area, etc. The metric system was adopted in Libya in 1927.
A number of different units of measurement were used in Tunisia to measure length, mass, capacity, etc. In Tunisia, Metric System has been compulsory since 1895.
References
- 1 2 3 4 Cardarelli, F. (2003). Encyclopaedia of Scientific Units, Weights and Measures. Their SI Equivalences and Origins . London: Springer. pp. 122, 125. ISBN 978-1-4471-1122-1.
- 1 2 3 4 5 6 Washburn, E.W. (1926). International Critical Tables of Numerical Data, Physics, Chemistry and Technology. Vol. 1. New York: McGraw-Hil Book Company, Inc. p. 9. Retrieved 8 February 2015.
- 1 2 Clarke, F.W. (1891). Weights Measures and Money of All Nations. New York: D. Appleton & Company. pp. 53.