The latent heat of vaporization is also extremely high, and large energy inputs are required before liquid water can be changed to a vapor. Consequently, water exists primarily as a liquid at common temperatures and pressures. The density of water also reveals interesting and unique properties. Water is the only common substance that expands when it freezes. This allows ice to float on water and causes surface waters to freeze from the top down.
Water also exhibits the highest surface tension of any known liquid except mercury.
In other words, the molecular attractions between adjacent water molecules at the air-water interface favor adhesion to the liquid phase. The resulting tension is sufficient to support particles and organisms of considerable size. Finally, water is an excellent solvent capable of dissolving a wide range of substances. He completed his Ph.D. in 1995 at McGill University in Montreal, Quebec, Canada. His current research efforts are largely focused on determining the sources, identity and health hazards of genotoxic substances in municipal wastewaters and surface waters.