Question

water, H2O, and methane, CH4, have about the same mass and differ by only one type of atom. Why is the boiling point of water so much higher than that of methane?

Answer 1

When water, or any substance, is boiled, its intermolecular forces are virtually non-existent. This is why they become gases after being boiled. The difference between H2O and CH4 is the presence of hydrogen intermolecular bonding between water molecules. Hydrogen bonds are the strongest type of intermolecular bond and require great deal of energy to break them. That's why water has a high boiling point.