Calculating Molar Mass

Basics of Molar Mass

• Molar Mass (M mass): Connects mass with moles
• Elemental Nitrogen:
  • Atomic number: 7
  • Average atomic mass: 14.01 g/mol
  • 1 mole of nitrogen = 14.01 g

Examples of Elemental Molar Mass

• Elemental Fluorine:
  • Atomic number: 9
  • Mass number: 19
  • 1 mole of fluorine atoms = 19 g

Calculating Molar Mass of Molecules

• Ozone (O3):

  • Contains 3 oxygen atoms
  • Atomic mass of oxygen: 16 g/mol
  • Molar mass of O3 = 3 * 16 = 48 g/mol

• Elemental Sulfur (S8):

  • Contains 8 sulfur atoms
  • Atomic mass of sulfur: 32.7 g/mol
  • Molar mass of S8 = 8 * 32.7 = 261.6 g/mol

More Complex Examples

• Carbon Dioxide (CO2):

  • 1 carbon atom (12.01 g/mol)
  • 2 oxygen atoms (2 * 16 g/mol = 32 g/mol)
  • Molar mass of CO2 = 12.01 + 32 = 44.01 g/mol

• Silicon Tetrafluoride (SiF4):

  • 1 silicon atom (28.9 g/mol)
  • 4 fluorine atoms (4 * 19 g/mol = 76 g/mol)
  • Molar mass of SiF4 = 28.9 + 76 = 104.9 g/mol

Molar Mass of Glucose (C6H12O6)

• Composition:
  • 6 carbon atoms: 6 * 12.01 = 72.06 g
  • 12 hydrogen atoms: 12 * 1.08 = 12.96 g
  • 6 oxygen atoms: 6 * 16 = 96 g
  • Total molar mass of glucose = 72.06 + 12.96 + 96 = 181.02 g/mol*

Molar Mass from Chemical Formula

• Calcium Phosphate (Ca3(PO4)2):

  • 3 calcium atoms: 3 * 40.08 = 120.24 g
  • 2 phosphorus atoms: 2 * 30.97 = 61.94 g
  • 8 oxygen atoms: 8 * 16 = 128 g
  • Total molar mass = 120.24 + 61.94 + 128 = 310.18 g/mol

• Vanadium(V) Hydrogen Phosphate (V2(HPO4)5):

  • 2 vanadium atoms: 2 * 50.94 = 101.88 g
  • 5 hydrogen atoms: 5 * 1.08 = 5.40 g
  • 5 phosphorus atoms: 5 * 30.97 = 154.85 g
  • 20 oxygen atoms: 20 * 16 = 320 g
  • Total molar mass = 101.88 + 5.40 + 154.85 + 320 = 582.13 g/mol*