Question

What is the formula mass of ammonia?

Answer 1

The formula of ammonia is `NH_3`.

Break the formula up to see what atoms are present. By that, you know that Nitrogen and Hydrogen are present.

If you look into the periodic table, you can see that the formula mass (or a.k.a molar mass) of Nitrogen is 14.0 g/mol and Hydrogen 1.0 g/mol.

Since there are 3 Hydrogen atoms present, the formula mass of H is 1.0 `xx`3 = 3.0 g/mol.

Therefore, by adding them up, the formula mass of ammonia is:
[14.0 g/mol + 3.0 g/mol] = 17.0 g/mol.

Periodic table source: Level 2 Chemistry SciPad (NZ syllabus)