Why does water (H2O) have a significantly higher boiling point compared to hydrogen sulfide (H2S), despite H2S having a higher molar mass?
Correct: C
Boiling point is directly related to the strength of intermolecular forces (IMFs). Both H2O and H2S are polar molecules and exhibit London Dispersion Forces and Dipole-Dipole interactions. However, water has a unique ability to form extensive hydrogen bonds due to the high electronegativity of oxygen and the small size of hydrogen. Hydrogen bonds are significantly stronger than the dipole-dipole interactions present in H2S (sulfur is less electronegative than oxygen, resulting in weaker bond polarity and thus weaker hydrogen bond donor/acceptor ability, if any significant H-bonding occurred at all for H2S, which it doesn't to a large extent). Therefore, the much stronger hydrogen bonding in water requires significantly more energy to overcome during boiling, leading to its exceptionally high boiling point compared to H2S, even though H2S has a higher molar mass.