Question

What is the number of particles in 6g of water

Answer 1

I think A mole is a convenient counting unit whenever one is dealing with numbers of atoms or molecules. It is equal to Avogadro's number (NA), namely 6.022x1023. If we have one mole of water, then we know that it will have a mass of 2 grams (for 2 moles of H atoms) + 16 grams (for one mole O atom) = 18grams.

Answer 2

18 g of water contain 1 mol of water molecules.
18 g of water contain 6.022 x 10^23 water molecules.
the number of water molecules present in 1 g of water is 3.3455 x 10^22.
Therefore 6g of water molecules = (6*1/18)=0.3529 moles
=2.125x 10^22 molecules