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The molecular mass (m) is the mass of a given molecule. The unit dalton (Da) is often used. [1] Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The derived quantity relative molecular mass is the unitless ratio of the mass of a molecule to the atomic mass ...
The molar mass of atoms of an element is given by the relative atomic mass of the element multiplied by the molar mass constant, M u ≈ 1 × 10 −3 kg/mol = 1 g/mol. For normal samples from earth with typical isotope composition, the atomic weight can be approximated by the standard atomic weight [2] or the conventional atomic weight.
Thus, the atomic mass of a carbon-12 atom is 12 Da by definition, but the relative isotopic mass of a carbon-12 atom is simply 12. The sum of relative isotopic masses of all atoms in a molecule is the relative molecular mass. The atomic mass of an isotope and the relative isotopic mass refers to a certain specific isotope of an element.
An atomic weight (relative atomic mass) of an element from a specified source is the ratio of the average mass per atom of the element to 1/12 of the mass of an atom of 12 C. The definition deliberately specifies " An atomic weight…", as an element will have different relative atomic masses depending on the source.
The molar mass constant, usually denoted by Mu, is a physical constant defined as one twelfth of the molar mass of carbon-12: Mu = M (12 C)/12. [1] The molar mass of an element or compound is its relative atomic mass (atomic weight) or relative molecular mass (molecular weight or formula weight) multiplied by the molar mass constant.
Thus, common chemical conventions apply to the definition of the constituent entities of a substance, in other cases exact definitions may be specified. The mass of a substance is equal to its relative atomic (or molecular) mass multiplied by the molar mass constant, which is almost exactly 1 g/mol.
Formerly called atomic/molecular weight. Example: A r (Cl) = 35.453. Both quantities depend on the nuclidic composition. relative molecular mass: M r: Ratio of the average mass per molecule or specified entity of a substance to 1/12 of the mass of an atom of the nuclide 12 C number of molecules or other elementary entities: N
Molar mass distribution. In polymer chemistry, the molar mass distribution (or molecular weight distribution) describes the relationship between the number of moles of each polymer species (Ni) and the molar mass (Mi) of that species. [1] In linear polymers, the individual polymer chains rarely have exactly the same degree of polymerization and ...