Askiitians Tutor Team
Last Activity: 9 Months ago
Relative atomic mass and relative molar mass are related concepts in chemistry but they refer to slightly different things:
Relative Atomic Mass (Ar):
Relative atomic mass (Ar) refers to the average mass of an atom of an element compared to 1/12th the mass of an atom of carbon-12.
It is a dimensionless quantity and is usually expressed in atomic mass units (amu) or unified atomic mass units (u).
Relative atomic mass takes into account the abundance of isotopes of the element.
For example, the relative atomic mass of carbon is approximately 12.01, which means that on average, a carbon atom is 12.01 times as massive as 1/12th the mass of a carbon-12 atom.
Relative Molar Mass (Mr):
Relative molar mass (Mr) refers to the mass of one mole of a substance compared to 1/12th the mass of an atom of carbon-12.
It is expressed in grams per mole (g/mol).
Relative molar mass considers the molecular or formula weight of a substance, taking into account the masses of all the atoms present in a molecule or formula unit.
For example, the relative molar mass of water (H2O) is approximately 18.02 g/mol, which means that one mole of water molecules has a mass of 18.02 grams.
In summary, relative atomic mass is specific to individual atoms of an element, while relative molar mass refers to the mass of one mole of a substance, whether it's an element or a compound.