دانلود کتاب H2O Just Ordinary Water

Our water is a marvellous solution – always on the move in thecycle of nature – and a condition for all life. Water is alwayschanging form, from liquid to vapour to ice, and back again.Water is cyclic and has been functioned this way for billions ofyears. Every life on Earth depends on water; computersimulation has shown that the DNA helix breaks apart if it ismodelled without water.Water is a chemical union of hydrogen and oxygen. The watermolecule is a dipole; the atoms are joined in an asymmetricalmanner that gives one end a surplus of positive electricalenergy and the other end a surplus of negative electricalenergy. Water is heaviest not at 0°C, its freezing point, but at+4°C. If it were heaviest at 0°C then ice would form first at thebottom of rivers and lakes; the fish would die and the ice wouldnot melt in the spring. Would there be life on earth in thatevent?