Question

Why do methane is a gas at room temperature and water is a liquid, even though both molecules are similar in size and mass?

Answer 1

Answer:

Water can hydrogen bond.

Explanation:

Liquids become gases once they are heated to a certain temperature. Heat is a form of energy. This change occurs when the intermolecular forces between the liquid molecules are energized enough to break. This breakage is necessary because gaseous molecules exist individually and do not interact with one another. That being said, it takes more heat to boil water because its intermolecular forces are stronger than methanes.

Intermolecular forces (IMF) are a result of partial charges on the molecular atoms that cause temporary bonds to form between molecules.

Methane is a nonpolar molecule, meaning each atom can only have slight partial charges. The strongest IMF methane participates in are London Dispersion Forces.

Water, however, is a polar molecule, with the hydrogens having strong partial positive charges and the oxygens having strong partial negative charges. This allows water to participate in a very strong IMF called hydrogen bonding. Again, because these partial charges are so strong, the water molecules can form stronger IMFs.

*When molecules have stronger IMFs, they require more energy(heat) to overcome them.*