Formula Mass

If you know the formula for a compound or an element it is then possible to calculate the formula mass or gram formula mass (GFM) for that compound or element.

The masses of atoms can be found by consulting the data booklet (page 7).

The masses of compounds can be calculated by considering the formula and the relative atomic masses of all the atoms in the compound.

An example of how to calculate the formula mass of a compound is shown below.

Calculate the formula mass of calcium oxide.

Another example:

Calculate the formula mass of magnesium hydroxide

Gram Formula Mass

When writing the gram formula mass of a substance the same process should be used and the unit grams (g) should be included after the value. For example the formula mass of sodium oxide is 62 and the gram formula mass (GFM) is 62g.

This is the end of topic 4.