# What is the formula weight of #Mg(BrO_4)_2#?

##### 1 Answer

#### Explanation:

The formula weight of magnesium perbromate can be obtained by using the following equation:

**atomic weight of element #xx#number of atoms given by subscript #=# formula mass**

First, you want to have a periodic table available so you can determine the atomic weight of Mg, Br, and O:

- Mg has a molar mass of 24.31 g/mol
- Br has an atomic weight of 79.90 g/mol
- O has an atomic weight of 16.00 g/mol

There is one magnesium atom, so the atomic mass of Mg is just 24.31 g/mol

From the chemical formula, we have 2 bromine atoms. Therefore, the atomic mass has to be multiplied by 2 to obtain an atomic weight of 159.80 g/mol.

There are 8 oxygen atoms, so the atomic mass has to be multiplied by 8, which gives you a value of 128.00 g/mol

Now you want to add the mass of each atom together to obtain the formula mass of the entire compound: