Final answer:
The higher boiling point of CH3OH over CH3SH is attributed to hydrogen bonding in CH3OH. CH3CH3 boils at a higher temperature than CH4 due to stronger dispersion forces from its larger molecular size. CSe2 has a higher boiling point than CS2 because of the stronger dispersion forces resulting from its larger size and electron count.
Step-by-step explanation:
Boiling Point Comparisons
The main reason that CH3OH has a higher boiling point than CH3SH is that CH3OH is capable of hydrogen bonding due to the OH (hydroxyl) group attached to the molecule. Hydrogen bonds are significantly stronger intermolecular forces than the dipole-dipole and London dispersion forces present in CH3SH, leading to a higher boiling point for CH3OH.
The reason that CH3CH3 has a higher boiling point than CH4 is due to the greater surface area and consequently stronger London dispersion forces in CH3CH3 as a consequence of its larger molecular size in comparison to CH4. Greater dispersion forces result in a higher amount of energy being required to separate the molecules, thus a higher boiling point.
Lastly, CSe2 has a higher boiling point than CS2 as CSe2 is larger and has more electrons, leading to stronger dispersion forces. This increased strength in intermolecular forces equates to a higher boiling point for CSe2 compared to CS2.