Hello, im studyng colligative properties and i learned that the boilling point of the substances are determinated by the intermolecular foces and the size of the molecule. So why is NH3 (small polar molecule with hydrogen bonds between then) WAY more volatile than H2O (small polar molecule with hydrogen bonds between then) ? 

Sorry for the gramatical erros, not a native english speaker here.

Thanks

There are two things.
Water can form two hydrogen bonds to other molecules; ammonia can only form 1
Also, while ammonia is much more volatile than water, it's much less volatile than, for example, methane.

Thank you