# What is the molar mass of iron (III) oxide (#Fe_2O_3#)?

##### 1 Answer

Dec 26, 2016

#### Explanation:

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

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

- Fe has an atomic weight of 55.85 g/mol
- O has an atomic weight of 16.00 g/mol

From the chemical formula, there are 2 iron atoms, so the atomic mass has to be multiplied by 2, which gives you a value of 111.7 g/mol

Next, you have 3 oxygen atoms, so you would multiply the atomic mass of O by 3 to obtain an atomic weight of 48.00 g/mol

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