Question

The boiling points for H₂O (BP=100 C) and H₂S (BP=-60 °C) are drastically different despite oxygen and sulfur being next to each other on the periodic table.

Choose the best explanation for this difference.
Select one:
a. H₂S is a larger molecule than H₂O and has stronger intermolecular forces.
b. H₂O is a larger molecule than H₂S and has stronger intermolecular forces.
c. H₂S has dipole-dipole forces, whereas H₂O does not. This moderately strong intermolecular force makes it more difficult for the H₂S molecules to transition from the liquid to the vapor phase.
d. H₂O can hydrogen bond, whereas H₂S cannot. This strong intermolecular force makes it more difficult for the H₂O molecules to transition from the liquid to the vapor phase.

Answer 1

The boiling point difference is due to H₂O's ability to form hydrogen bonds, a strong intermolecular force absent in H₂S, leading to a much higher boiling point for water.

Step-by-step explanation:

The drastic difference in boiling points between H₂O and H₂S can be attributed to the presence of hydrogen bonds in water, which are not found in hydrogen sulfide. While both H₂O and H₂S are composed of a hydrogen atom bonded to an adjacent element on the periodic table (oxygen and sulfur, respectively), oxygen is much more electronegative than sulfur.

This difference in electronegativity enables water to form hydrogen bonds, significantly increasing its boiling point compared to H₂S. Hence, option d is correct: H₂O can hydrogen bond, whereas H₂S cannot. This strong intermolecular force makes it more difficult for the H₂O molecules to transition from the liquid to the vapor phase.