# What is the formula mass of #HNO_3#?

##### 1 Answer

The formula mass of

#### 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 H, N and O:

- H has an atomic weight of 1.008 g/mol
- N has an atomic weight of 14.01 g/mol
- O has an atomic weight of 16.00 g/mol

From the chemical formula, we have 1 hydrogen atom, so the atomic mass would just be 1.008 g/mol

There is also 1 nitrogen atom, so the atomic mass is just 14.01 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: