# How can I calculate the molar mass?

Sep 30, 2014

To calculate the molar mass of a compound, first determine the number of atoms of each type in each molecule and then add up the atomic masses.

Example: Find the molar mass of ethanol, ${C}_{2} {H}_{5} O H$

Each molecule in this compound has 2 carbon atoms, 6 hydrogen atoms, and 1 oxygen atom. The atomic masses, from the periodic table of elements are:

C - 12.011 g/mol
H - 1.008 g/mol
O - 15.999 g/mol

The molar mass of ethanol is then
$2 \times 12.011 + 6 \times 1.008 + 1 \times 15.999 = 46.069$ g/mol