Although water and ammonia differ in molar mass by only one unit, the boiling point of water is over 100 degrees C higher than that of ammonia. What forces in liquid water that do not exist in liquid ammonia could account for this observation?

Answer 1

I think the major difference is the electronegativity of N versus that of O. Both NH3 and H2O have hydrogen bonding but the strength of that bond is more in H2O than in NH3. That may not answer your question since the questions asks for DIFFERENT forces present in water and not present in NH3. I wonder what the surface tension is for NH3 and could that account for over 100 C

Answer 2

they both have hydrogen bonding yet; H20 has a stronger Hydrogen bonding ;)