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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).
After the metre was redefined in 1960, the International Prototype of the Kilogram (IPK) was the only physical artefact upon which base units (directly the kilogram and indirectly the ampere, mole and candela) depended for their definition, making these units subject to periodic comparisons of national standard kilograms with the IPK. [38]
Here’s why correctly quantifying mass is more important than you think. Scientists want to define the kilogram by gravity—and not just electricity. Here’s why correctly quantifying mass is ...
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]
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 ...