Convert Dalton to Kilogram

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Dalton

The dalton (Da) or unified atomic mass unit (u) is a unit of mass used to express atomic and molecular weights. It is defined as one twelfth of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and it is approximately equal to 1.66053906660 × 10⁻²⁷ kg.

Origin:

The dalton is named after the English chemist and physicist John Dalton, who developed the atomic theory of matter. The unit was adopted in 1961 by the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP) to provide a standardized unit for atomic and molecular weights.

Kilogram

The kilogram (kg) is the base unit of mass in the International System of Units (SI). It is defined based on the Planck constant (h), a fundamental constant of nature.

1 kilogram is the mass that corresponds to the fixed numerical value of the Planck constant (h), which is 6.62607015 × 10⁻³⁴ joule-seconds (J·s), when expressed in the SI unit J·s = kg·m²·s⁻¹.

This modern definition ties the kilogram to a constant of nature rather than a physical object, ensuring its precision and stability over time.

Before this redefinition, the kilogram was defined as the mass of the International Prototype of the Kilogram (IPK), a physical platinum-iridium cylinder stored in France.

Origin:

The kilogram originated during the French Revolution in the late 18th century as part of the metric system's development. Initially, it was defined as the mass of one cubic decimeter of pure water at 4°C, chosen for its universal availability and consistency. In 1799, a physical standard called the Kilogram of the Archives, a platinum cylinder, was created to represent the unit. Later, in 1889, the International Prototype of the Kilogram (IPK), a more precise platinum-iridium cylinder, was adopted as the global standard, stored in France with copies distributed worldwide.

Over time, physical changes in the IPK led to inconsistencies, prompting scientists to redefine the kilogram. In 2019, it was redefined based on the Planck constant (h), a fundamental constant of nature, linking the kilogram to unchanging physical properties rather than a physical object. This modern definition ensures long-term precision and stability for the unit of mass.