# Finding the volume of one water molecule

by Niles
Tags: molecule, volume, water
 P: 1,863 1. The problem statement, all variables and given/known data Hi guys I know the molar mass (i.e. g/mole) of H and O, but from this, then how do I find the volume of 1 water molecule? I know the densities of H and O as well, from which I can find the volume of H and O. Do I just add these, one of V_oxygen and two of V_hydrogen (I know the correct value is 2.99E-29 kg^3)? I tried doing this, but it did not give me the correct value. Best, Niles.
 Admin P: 22,361 You better start with water density (1g/mL) and calculate how many molecules in 1mL. Assuming final volume of a molecule is a sum of volumes of atoms is a sure way of getting it wrong. How come final answer is in kg3? You sure you didn't mean m3? --
 P: 1,863 I mixed it up - the volume is of course in m^3. Regarding the density, then what I wanted was a general way of doing it, because I might not always know the density of the molecule as a whole, but only each atomic-part of the molecule. So, how should I do it? I can find V_H and V_O, but adding them as 2V_H + V_O doesn't give me the correct result.