Question

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

Answer 1

`"342.13 g/mol"`

Explanation:

The molar mass of `Al_2(SO_4)_3` can be determined by adding the individual masses of each atom. These masses can easily be obtained from a periodic table.

Start with `Al_2`

The atomic mass is `"26.982 g/mol"`.

But there are two `Al` so multiple by 2 and get `"53.964 g/mol"`
Leave this number here for now. We will revisit this later.

Now we have to calculate for `(SO_4)_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 `"96.062 g/mol"`.

Wait! There are three sulphates so multiply by 3. The answer should be `"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 :-)

`"(53.946+288.186) g/mol" = "342.132 g/mol"`