Formula Mass and Molar Mass

Formula Mass

Definition

The formula mass () is the mass of one molecule of an element or compound (total mass of all atoms in a molecule), i.e AMU

Examples

Formula mass of :
Formula mass of :

Molar Mass

Definition

The molar mass () is the mass of one mole of substance, i.e amu -> mol

Examples

  • The mass of one mole of molecules is , so the molar mass of is
  • The mass of one mole of molecules is , so the molar mass of is

Example

Molar mass of

Example

Molar mass of

Note that the 2 is from the subscript from , and the coefficient is ignored, as molar mass is a RATIO

You can calculate the molar mass of a compound by adding up the atomic numbers multiplied by the subscripts properly