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THE STRANGE BEHAVIOUR OF THE WATER

   

       We all know water is made up of H2O molecule.  The molecule is 'V' shaped; oxygen at the vertex and two hydrogen at the edges.  The oxygen has more electrons (16).  Hence the molecules is more negative on oxygen side and slightly positive on hydrogen side.  We say, this molecule acts like electric dipole.  Hence there is attraction between oxygen of one molecule and hydrogen of another molecule.  We call this attraction as "hydrogen bonding".  Because of the hydrogen bonding, the molecules cling together as droplets, drops , liquid,  ice, ice crystals.

     Top surface of the water in a container is called free-surface.  Above the free-surface -No forces.  But below the free surface, there are attractive forces due to hydrogen bonding.  Hence top surface is pulled inwards and looks curved.  All the water surfaces are always under tension.  If you jump into a big well containing water, you will feel pain in the chest due to surface tension(here the surface acts like a steel sheet).  You can throw a stone before jumping to break surface tension.

     Since there is a downward force on the surface, there will be upward force due to reaction.  The upward forces raises water in the plants; blood in the body; oil in a wick of a lamp.

     It takes large amount of heat to break hydrogen bonding between molecules.  Hence water requires large amount of heat to raise its temperature.  Remember water's boiling point is very high(100 degree c).  All other substances requires much less heat than water.  Because of this property, water is cold in the well in summer and hot in the winter.  Sea breeze and land breeze also occurs due to this property.

     Again due to hydrogen bonding water expands while freezing (contrary to other substances).  Hence ice is less denser  and it  floats above water.

     At 0 degree c, the three forms of water; ice; liquid and vapour co-exist.

    If we put a spoon full of salt, into water, it dissolves.  How?  We know, salt is just sodium chloride.  The negative side of water molecules (oxygen) surround positive sodium ion of salt and pulls it apart.  Similarly positive side of water molecules (hydrogen) surround negative chlorine ion and rips it apart.  Hence salt dissolves.  Most substances dissolve in water.

     Body fluids are mainly made up of water.  The hydrogen bonding gives us many life-sustaining properties.

     Appreciate the nature's ingenuity.
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