Fx H<sub>2</sub>O ([[vand]]). For at beregne molvægten af H<sub>2</sub>O adderes to H-atomers ([[hydrogen]]) masse med hinanden. Herefter adderes et O-atoms ([[oxygen]]) masse til de 2 H-atomers masse. Altså: (1,008*2)+16 = 18,016 g/mol
== Links ==
* [http://chemistry-in-excel.jimdo.com Stoichiometry Add-In for Microsoft Excel] for calculation of molecular weights, reaction coëfficients and stoichiometry.
