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The International Prototype of the Kilogram (referred to by metrologists as the IPK or Le Grand K; sometimes called the ur-kilogram, [1] [2] or urkilogram, [3] particularly by German-language authors writing in English [3] [4]:30 [5]: 64 ) is an object whose mass was used to define the kilogram from 1889, when it replaced the Kilogramme des ...
It had a mass equal to the mass of 1 dm 3 of water at the temperature of its maximum density, which is approximately 4 °C. [13] 1875–1889: The Metre Convention was signed in 1875, leading to the production of the International Prototype of the Kilogram (IPK) in 1879 and its adoption in 1889. [14]
As with a definition based upon carbon‑12, the Avogadro constant would also have been fixed. The kilogram would then have been defined as "the mass equal to that of precisely 1000 / 196.966 5687 × 6.022 141 79 × 10 23 atoms of gold" (precisely 3 057 443 620 887 933 963 384 315 atoms of gold or about 5.077 003 71 fixed moles).
The modern kilogram has its origins in the Age of Enlightenment and the French Revolution.In 1790 an influential proposal by Talleyrand called for a new system of units, including a unit of length derived from an invariable length in nature, and a unit of mass (then called weight) equal to the mass of a unit volume of water. [4]
The international prototype of the kilogram (IPK) is an artefact or prototype that was defined to have a mass of exactly one kilogram.. In metrology (the science of measurement), a standard (or etalon) is an object, system, or experiment that bears a defined relationship to a unit of measurement of a physical quantity. [1]
kg/m 3: density: ρ: kilogram per square metre kg/m 2: surface density: ρ A: cubic metre per kilogram m 3 /kg: specific volume: v: ampere per square metre A/m 2: current density: j: ampere per metre: A/m: magnetic field strength: H: mole per cubic metre mol/m 3: concentration: c: kilogram per cubic metre: kg/m 3: mass concentration: ρ, γ ...
Appendix 2 to the 9th SI Brochure states that "the molar mass of carbon 12, M(12 C), is equal to 0.012 kg⋅mol −1 within a relative standard uncertainty equal to that of the recommended value of N A h at the time this Resolution was adopted, namely 4.5 × 10 −10, and that in the future its value will be determined experimentally", [49] [50 ...
[3] [4] Prior to 2019, the definition of the kilogram was based on a physical object known as the International Prototype of the Kilogram (IPK). After considering alternatives, in 2013 the General Conference on Weights and Measures (CGPM) agreed on accuracy criteria for replacing this definition with one based on the use of a Kibble balance.