Question

What is the molecular mass of `NH_3`?

Answer 1

17.031 g/mol

Explanation:

In order to find the molecular mass, the first thing you want to do is get a periodic table. Next look for each element and determine the atomic weight of each element separately. In our case we are dealing with ammonia, which contains nitrogen and hydrogen.

The atomic weight of an element is listed under its chemical symbol. Nitrogen has an atomic weight of 14.0067 g/mol and hydrogen has an atomic weight of 1.008 g/mol. Since there are three hydrogen atoms the atomic weight has to be multiplied by 3 to get a value of 3.024 g/mol. Remember, the mass of an element must be multiplied by the number of atoms of that element.

For example:

1 N atom = 14.0067 g/mol (1) = 14.0067 g/mol
3 H atoms = 1.008 g/mol (3) = 3.024 g/mol

Afterwards you just add the masses of each element together to obtain the molecular mass like so:
14.0067 g/mol `+` 3.024 g/mol `=` 17.031 g/mol