Final answer:
Water's melting and boiling points are unusually high compared to similar compounds due to hydrogen bonding, which requires more energy to break. This unique feature allows water to exist as a liquid over a range of temperatures, supporting life on Earth.
Step-by-step explanation:
Water is indeed unique in terms of its melting point and boiling point compared to similar compounds such as hydrogen sulfide (H2S) and ammonia (NH3). This uniqueness derives from the hydrogen bonds between water molecules, which are stronger than typical intermolecular forces.
The effect of this hydrogen bonding raises the energy required to break these bonds and transform water from a solid to a liquid state (melting point) and from a liquid state to a gaseous state (boiling point). Thus, water's melting point and boiling point are higher than those of similar molecular weight compounds.
For instance, water's melting point is 0°C while that of hydrogen sulfide is -82°C, and water's boiling point is 100°C while that of ammonia is -33°C. It's this extraordinary characteristic that allows water to exist as a liquid under a wide range of temperatures on Earth, which is essential to support life.
Learn more about Water's unique properties