Question

molecular mass of water is 18 u . what will be the number of molecules of water in 18 g water

Answer 1

Molecular weight of water = 18 g/mol

Given weight = 18 g

So, number of moles n = (Given Weight)÷(Molecular Weight)

So, n = 18/18 = 1 mole


Now, 1 mole of any entity contains
6.022 × 10^23 units of that entity.
(This number is called the Avogadro Number)


So, in 1 mole water, there are 6.022 × 10^23 molecules