What Is A Mol?

The mol is a key concept for any level of chemistry, so it is important to understand what it is and what it is used for.

The definition of a mol is "The amount of a substance that has the same weight as 1/12 of a C¹² atom"

What this means is if an element has an atomic weight of 20 (for example), 1 mol of the element will weigh 20 grams.

If a molecule of O₂ has molecular weight of 32, how much does:

a) 1 mol weigh?

b) 1/2 mol weigh?

c) 2 mol weigh?

A: 32 x 1 = 32g

B: 1/2 x 32 = 16g

C: 2 x 32 = 64g

Now that you understand mols, where are they used?

The first main case is in using the formula Mr (molecular mass) x mol = mass

The second main case is in using the formula concentration = mols/volume

The third main case is in balanced equations, as in the Haber process:

N₂ + 3H₂ __> 2NH₃

This means that for every 1 mol of N₂, you need 3 mols of H₂. These combine to make 2 mols of NH₃

Thank you for reading this article! I hope it helped. Feel free to message me if you have any questions (about this article or any other questions)!