PROPERTIES OF WATER SUBSTANCE

WATER IS A POLAR LIQUID AS ARE HYDROGEN FLUORIDE AND HYDROGEN CYANIDE. POLAR LIQUIDS ARE MADE UP OF SMALL MOLECULES CONTAINING HYDROGEN WHICH IS SUFFICIENTLY MOBILE OR ACTIVE TO SERVE AS A LINK BETWEEN MOLECULES. WATER IS A LIQUID WITH STRUCTURE SUCH THAT THE MOLECULES ARE LINKED TOGETHER BY HYDROGEN BONDS SO THAT THEY ARE NOT FREE TO ROTATE AS ARE BENZENE MOLECULES IN LIQUID BENZENE. THE WHOLE MASS OF LIQUID WATER CONSTITUTES THE MOLECULE. THE MOLECULAR WEIGHT DEPENDS ON THE SIZE OF THE CONTAINING VESSEL. THE BEST METHOD FOR THE DETECTION OF HYDROGEN BONDS IS INFRARED ABSORPTION. THE ONLY PROPERTIES WHICH DIFFER MARKEDLY FOR ICE AND WATER ARE DENSITY AND VISCOSITY AND CLOSELY RELATED PROPERTIES. THE INFRARED ABSORPTION, THE DIELECTRIC CONSTANT, AND THE DEGREE OF ASSOCIATION CHANGE IN A CONTINUOUS MANNER THROUGH THE MELTING POINT. WATER IS ONE OF THE FEW SUBSTANCES WHICH SHOWS A GREATER DENSITY AS A LIQUID THAN AS A SOLID, AND IT IS PERHAPS THE ONLY SUBSTANCE THAT EXHIBITS A MAXIMUM DENSITY A FEW DEGREES ABOVE THE FREEZING POINT. THE EXACT ARRANGEMENT OF THE WATER MOLECULES IN THE ICE CRYSTAL IS NOT KNOWN WITH CERTAINTY, BUT IT IS KNOWN THAT WATER MOLECULES ARE ARRANGED IN HEXAGONAL RINGS WHICH FORM A NETWORK OR LATTICE. WHEN ICE MELTS TO LIQUID WATER THE HYDROGEN BONDS ARE STRETCHED AND THE MOLECULES MOVE FARTHER APART. THIS HAS CONSEQUENCES WHICH AFFECT THE VISCOSITY, DIELECTRIC CONSTANT, AND ELECTRIC CONDUCTIVITY. THE FOLLOWING PROPERTIES ARE DISCUSSED: VISCOSITY, HEAT CAPACITY, AND LIQUID STRUCTURE. THE PICTURE OF WATER AS A LARGELY ASSOCIATED STRUCTURE OF HIGH DIELECTRIC CONSTANT ACCOUNTS FOR ITS EXTRAORDINARY ABILITY TO ACT AS A SOLVENT FOR ELECTROLYTES. SOLUTIONS OF NONPOLAR MOLECULES ARE DESCRIBED BECAUSE THEY HAVE THE EFFECT AUGMENTING THE STRUCTURE OF WATER. THE IONIC HYDRATION AND MOBILITY ARE DESCRIBED IN REFERENCE TO THE MOLECULAR CLUSTERS OBSERVED. LIQUID WATER UNDERGOES A CHANGE IN STRUCTURE IN THE PRESENCE OF MOLECULES OR AT THE SURFACE OR INTERFACE OF A SOLID PHASE. THIS EFFECT IS DESCRIBED AS BOUND WATER, SINCE WATER TENDS TO SOLIDIFY OR CRYSTALIZE IN THE PRESENCE OF FOREIGN MOLECULES. THE GEOLOGICAL WEATHERING OF CLAYS PRODUCES A VARIETY OF COLLOID BEHAVIOR IN WHICH WATER BEHAVES AS A PLASTICIZER. THIS PLASTICIZING ACTION INVOLVES THE HYDROGEN BONDING OF WATER TO THE OXYGEN OF THE SILICA OR ALUMINA GROUPS. THIS BONDING OF THE WATER MOLECULES IS A MORE OR LESS REVERSIBLE PROCESS EXCEPT WHEN HIGH TEMPERATURES ARE REACHED, IN WHICH CASE THE MOLECULES BECOME SO CLOSELY BONDED THAT THE WATER MOLECULES CANNOT INTRUDE.

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Filing Info

  • Accession Number: 00237878
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 17 1970 12:00AM