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# How would you differentiate between relative atomic mass and relative molar mass?

Last updated date: 12th Jul 2024
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Complete step-by-step answer:As we know the atoms are very small particles and so their masses are extremely less. Nowadays, the atomic masses of elements can be determined by the use of spectroscopy. But if we go back to the nineteenth-century, the relative atomic masses of the elements were used to find the mass of an atom. The atom of hydrogen was considered the standard mass as it weighed $1$ without the use of any units. Other elements of the periodic table were compared with the known atomic mass of the hydrogen element. At present the atomic mass of the carbon $12$ is used as the standard, for the determination of relative atomic masses of the substances. One atomic mass unit or also called ‘amu’ can be defined as the mass of ${{\dfrac{1}{12}}^{th}}$ of the carbon $12$. This unit ‘amu’ has been replaced with ‘u’ over the course of time to denote the atomic mass unit of an atom.
On the other hand the molar mass of a substance is the mass of one mole of any substance. And we know that one mole of any substance contains $6.022\times {{10}^{23}}$ number of particles. The relative molar mass can be defined as the lowest mass in its unit of a molecule or a compound which has one twelfth of the mass of one carbon $12$.
Note:The relative molar mass of neon is $20.1797{ }\dfrac{g}{mol}$ which is also its relative atomic mass. But this isn’t applicable in case of compounds or molecules like sodium hydroxide, whose relative molar mass is $39.9959{ }gmo{{l}^{-1}}$ which isn’t the relative atomic mass as it is not an atom.