Question

Atomic mass of oxygen is 16 u but its molecular mass is 32 u

Answer 1

HELLO THERE!

The reason is explained by Atomicity.

The number of atoms of an element/compound present in one molecule of it is called Atomicity.

Atomic mass of Oxygen (O) is 16 units.

However, Oxygen is a diatomic gas, i.e., one molecule of oxygen contains two atoms of oxygen. So, mass of 1 molecule of Oxygen must be Atomic mass x 2 = 16 x 2 = 32 units.

So, atomic mass of Oxygen = 16u.

But, molecular mass (containing two atoms) = 16 x 2 = 32 u.

THANKS!

Answer 2

oxygen is a non-metallic gas which makes a double covalent bond with another oxygen molecule and forms a diatomic molecule and hence its molecular mass is:
O² = [O] + [O]
=> 16u + 16u
=> 32u