What is the number of particles in 15.0 g of H2O?

We know that 18 g of H2O contains 1 mole (or 6.022 x 10^23) molecules of water because the molar mass of H2O is 18 g/mol.

So 1 g water will contain 1/18 moles of H2O molecules.

Now 15 g of water will contain 15/18 moles of H2O.

So molecules of H2O = (15/18) x 6.022 x 10^23 = 5 x 10^23 molecules.

Explanation:

I learned this in science hope this helps.