chemistry technology

Water is one of the most important of all chemical substances. It is the chief constituent of living matter. Its physical properties are strikingly different from those of other substances.
Ordinary water is impure, it usually contains dissolved salts and dissolved gases, and sometimes organic matter. For chemical work water is purified by distillation. Pure tin vessels and pipes are often used for storing and transporting distilled water. Glass vessels are not satisfactory, because the alkaline constituents of glass slowly dissolve in water. Distilling apparatus and vessels made of fused silica are used in making very pure water. The impurity, which is hardest to keep out of water, is carbon dioxide, which dissolves readily from the air.
The physical properties of water. Water is a clear, transparent liquid, colorless in thin layers. Thick layers  of  water  have  a  bluish-green  color.  Pure  water  freezes  at  0oC,  and  boils  at  100oC.  These temperatures are means of identifying water, for no other substance has these freezing and boiling points.
The physical properties of water are used to define many physical constants and units. The unit of mass  in  the  metric  system  is  chosen  so  that  1  cm3   of  water  at  4oC/  the  temperature  of   its  maximum density/ weighs 1.00000 gram. A similar relation holds in the English system: 1 cu. Ft. of water weighs approximately 1,000 ounces.
Steam and ice
Steam  is  water  in  the  gaseous  state.  A  cubic  inch  of  water  gives  about  a  cubic  foot  of  steam. When  gaseous  water   is  mixed  with  other  gases,  as  in  the  air,  we  speak  of  it  as  water  vapor;  when unmixed,  we  call  it  steam.  Water  may  exist  as  steam  at  temperature  lower  than  100oC,  provided  the pressure is less than the usual atmospheric pressure of 15 pounds per square inch.
If water is cooled sufficiently, it solidifies at 00C to ice. There is considerable expansion during
the solidification, and consequently ice is lighter than an equal volume of water.
If we apply heat to ice, it melts. The water that runs off the melting ice is at a temperature of 00C,
the same temperature as the ice.