1.1 Moles & Molar Mass Overview

1.1 Moles & Molar Mass

  • Purpose: Connect atomic-scale masses to macroscopic quantities via the mole concept.
  • Key definitions:
    • Molar Mass, M: the mass per mole of a substance. For elements, equals atomic weight (AW) in g/mol; for compounds, equals formula weight (FW) in g/mol. In practice: M = AW (or FW) in g/mol.
    • Atomic Mass Unit (amu): 1 amu is defined so that Hydrogen-1 is exactly 1.0000 amu; atoms with mass numbers are measured in amu. In conversions from amu to grams, 1 amu corresponds to 1 g per mole (conceptual linkage).
    • Avogadro’s Number, NA: N</em>A=6.022×1023N</em>A = 6.022\times 10^{23} particles per mole.
    • 1 mole: the amount of substance containing NAN_A elementary entities (atoms, molecules, etc.). Also, 1 mole of a substance has a mass numerically equal to its formula weight in amu (g/mol) in