# What is the molar mass of Al_2(SO_4)_3?

May 31, 2016

$\text{342.13 g/mol}$

#### Explanation:

The molar mass of $A {l}_{2} {\left(S {O}_{4}\right)}_{3}$ can be determined by adding the individual masses of each atom. These masses can easily be obtained from a periodic table.

Start with $A {l}_{2}$

The atomic mass is $\text{26.982 g/mol}$.

But there are two $A l$ so multiple by 2 and get $\text{53.964 g/mol}$
Leave this number here for now. We will revisit this later.

Now we have to calculate for ${\left(S {O}_{4}\right)}_{3}$

Same thing! Add the atomic masses from the periodic table. Remember there are 4 oxygens per sulfur! Add all those and you should get an answer close to $\text{96.062 g/mol}$.

Wait! There are three sulphates so multiply by 3. The answer should be $\text{288.186 g/mol}$

The question asks for the molar mass of the two ions I just calculated for. Simply add the two results for your answer :-)

$\text{(53.946+288.186) g/mol" = "342.132 g/mol}$