# Question #8ede8

Jun 29, 2015

The molar mass of aluminium sulfate is 342.2 g/mol.

#### Explanation:

Aluminium sulfate is an ionic compound with the formula $A {l}_{2} {\left(S {O}_{4}\right)}_{3}$.

It is formed when 2 aluminium cations, $A {l}^{3 +}$, bond to 3 sulfate anions, $S {O}_{4}^{2 -}$.

To get the molar mass of the compound you need to add the molar masses of all the atoms that form the aluminium sulfate formula unit.

This means that you have

• two atoms of aluminium - $2 \cdot \text{27.0 g/mol}$
• three atom of sulfur - $3 \cdot \text{32.07 g/mol}$
• twelve atoms of oxygen - $12 \cdot \text{16.0 g/mol}$

The molar mass of the compound will thus be

${M}_{M} = \textcolor{g r e e n}{\text{342.2 g/mol}}$