According to the modern IUPAC scale, the atomic mass unit (amu or u) is defined as exactly the mass — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
According to the modern IUPAC scale, the atomic mass unit (amu or u) is defined as exactly $1/12^{\text{th}}$ the mass of a Carbon-12 atom. If we hypothetically redefine the relative atomic mass unit to be exactly $1/6^{\text{th}}$ the mass of a Carbon-12 atom, how would the actual physical mass of one mole of a given substance be affected?
💡 Solution & Explanation
The mass of one mole of a substance is a macroscopic physical quantity defined by Avogadro's number of particles ($N_A$) and their absolute actual mass in grams. While changing the definition of the atomic mass unit (amu) alters the relative numerical value of atomic weights on the periodic table, "one mole" of a substance represents a physical aggregate of $6.022 \times 10^{23}$ molecules whose absolute mass in grams physically remains unchanged.