You're right to ask this! It seems counterintuitive that water, a relatively small molecule, has a higher boiling point than ethane, a much larger molecule. Here's why:

Hydrogen Bonding

* Water (H₂O): Water molecules are capable of forming strong hydrogen bonds with each other. Hydrogen bonds are a type of intermolecular force (forces between molecules) where a hydrogen atom is attracted to a highly electronegative atom (like oxygen) on a neighboring molecule. These bonds are relatively strong and require a significant amount of energy to break.

* Ethane (C₂H₆): Ethane molecules only experience weaker van der Waals forces, which are temporary and less powerful than hydrogen bonds. These forces arise from temporary fluctuations in electron distribution within the molecule.

The Result

* High Boiling Point of Water: Because of the strong hydrogen bonds between water molecules, it takes a lot of energy (heat) to overcome these attractions and allow the water to transition from a liquid to a gas (boiling). This results in a high boiling point of 100°C (212°F).

* Lower Boiling Point of Ethane: The weaker van der Waals forces in ethane are easier to overcome, resulting in a much lower boiling point of -88.6°C (-127.5°F).

In summary: The presence of strong hydrogen bonds between water molecules is the primary reason why water has a much higher boiling point than ethane, even though ethane is a larger molecule.