A unique substance Water is essential to all life on earth and dominates the chemical composition of all biota. Its necessity and ubiquity rest on its unique chemical and physical properties.
Water has an incredibly high specific heat, exceeded by few known substances.
As a result, water is thermally stable, with temperature changes occurring only very gradually. 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.